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I'lnZE  ESSAY  OF  THE  ALUMNI  ASSOCIATION 

OF  THE 

College  of  Physicians  and  Surgeons, 

NEW    YORK,  1873. 
♦ 

 ♦♦-.•4    - 

THE  EFFECTS 

O  F 

High  Atmospheric  Pressiire. 

IN(M.UI)IN(;  THK 

CA J  SSCm  DISEA  SP]. 

Hv  ANDREW  H.  SMITH,  M.  1).. 

>#SlTR<}EON  TO  THK  NKW  YOKK  BRIDCK  (.'oMI'ANV, 

Mkmbkk   ok  the   Acadkmy   ok   Natural   Sciknoks,    Phji.ai>ki.i"hia  ; 

C'ORHKSPONDINtJ   MK.MBKR   OK   THK  (iESKLLSCHAFT  FUR  HEII.K  i:NJ)E. 

Berlin;  late  ok  the  Medical  jStakk  of  the  Re(;ui  ak 
Armv;  Sur(;eon  to  the  Throat  Department  of  the 
Manha'itan  Eve  and  Ear  Hospital;  Physician 
to  St.  Luke's  Hosfital,  etc. 


lUiOOKLYN  : 


PRIZE  ESSAY  OF  THE  ALUMM  ASSOCIATION 

OF  THE 

College  of  Physicians  and  Surgeons, 

NEW    YORK,  1873. 


THE  EFFECTS 

OP 

High  atmospheric  Pressure, 

INCLUDING  THE 

CAISSOISr  DISEASE. 

Br  ANDREW  H.  SMITH,  M.  D, 

SURGKON  TO  THE  NEW  YORK  BRIDGE  COMPANY, 
# 

Member   of  the   Academy   ok  Natural   Sciences,  Philadelphia; 

CORRESPONDING   MEMBER   OF   THE   GESELLSCHAFT  FUR  HEILKUNDE, 

Berlin;  late  of  the  Medical  Staff  of  the  Regular 
Army  ;  Surgeon  to  the  Throat  Department  of  the 
Manhattan  Eye  and  Ear  Hospital  ;  Physician 
TO  St.  Luke's  Hospital,  etc. 


BROOKLYN: 
EAGLE  PRINT,  34,  36  and  38  FULTOX  STREET. 

1873. 


'1 


• 


EEPORT 

ON 

THE  EFFECTS  OF  HIGH  ATMOSPHERIC  PRESSORE, 

INCLUDING  THE 

C^ISSO]Sr  DISEASE. 

By  ANDREW  II    SMITH,  M.  D., 

Surgeon  to  the  Company. 


To  the  Board  of  Directors  of  the  Neto  York  Bridge  Company  : 
Gentlemen  : — 

This  Report  was  originally  inteuded  simply  to  present  my  own  ex- 
perience as  Surgeon  to  the  New  York  Bridge  Company  during  the 
sinking  of  the  second  caisson.  But  in  endeavoring  to  compare  this 
experience  with  that  of  others  who  had  had  opportunities  of  observ- 
ing the  effects  of  high  atmospheric  pressure,  I  found  tliat  the  litera- 
ture of  the  subject  consisted  only  of  isolated  reports  by  different 
individuals,  in  different  languages,  and  having  little  or  no  reference 
one  to  another,  so  that  a  great  deal  of  research  was  required  to  obtain 
a  connected  view  of  the  subject.  It  seemed  to  me,  therefore,  de- 
sirable not  to  add  another  to  the  list  of  disjointed  fragments,  but 
rather  to  incorporate  my  own  observations  with  the  existing  mate- 
rial, and  thus^resent  in  one  view  a  resume  of  our  actual  knowledge 
upon  the  subject.  This  I  have  endeavored  to  do  briefly  in  the  follow- 
ing pages.  For  whatever  is  purely  theoretical,  however,  and  espe- 
cially as  regards  the  pathology  of  the  Caisson  Disease,  I  must  accept 
the  entu'e  responsibility,  unless  reference  is  made  to  other  authority. 


CHAPTER  FIRST. 

HISTORY. 

The  discoveries  of  Torricelli,  in  1643,  which  led  to  his  invention  of 
the  barometer,  and  the  further  elucidation  by  Pascal  of  the  principles 
of  atmospheric  pressm-e,  five  years  later,  were  followed  by  confused 
and  contradictory  speculations  on  every  hand  as  to  what  would  be 
the  effect  upon  animal  life  if  the  barometric  changes  so  eagerly 
observed  assumed  a  wider  range. 

Dr.  Henshaw,  an  English  physician,  published  an  essay  in  1664,  in 
which  he  proposed  to  treat  diseases  by  varying  the  pressure  of  the 
atmosphere  by  w^hich  the  patient  was  surrounded.  His  idea  was  to 
have  a  room  (domicilium)  constructed  of  masonry,  and  made  air- 


4 


tight,  in  which  the  sick  person  could  remain  in  an  atmosphere  which 
was  to  be  either  rarefied  or  condensed  by  the  action  of  an  organ 
bellows. 

He  fancied  that  acute  diseases  would  be  benefited  by  an  increased 
pressure,  while  chronic  diseases  on  the  other  hand  demanded  a  rare- 
fied atmosphere.  His  views  seem,  however,  to  have  been  purely  theo- 
retical, as  there  is  no  record  of  any  serious  attempt  to  reduce  them  to 
practice. 

More  than  a  century  elapsed  before  the  subject  again  awakened  the 
attention  of  scientific  men.  In  the  year  1783  the  Academy  of  Sci- 
ences of  Haarlem  offered  a  prize  for  a  description  of  the  best  appara- 
tus for  experimenting  upon  the  effects  of  compressed  air,  with  a 
record  of  experiments  made  by  means  of  it  on  animal  life,  the  growth 
of  plants,  and  the  inflammability  of  the  different  gases.  This 
prize,  however,  was  not  contended  for  until  more  than  half  a  century 
later. 

Diving-bells  were  brought  into  use  as  early  as  the  beginning  of  the 
sixteenth  centmy,  but  the  condensation  of  the  air  within  them  does 
not  seem  to  have  attracted  attention,  at  least  as  affecting  the  occu- 
pant. Indeed,  whatever  influence  the  increased  pressure  may  have 
exerted  was  masked  by  the  j.mpurity  of  the  air,  which,  in  the  ma- 
chines first  employed,  was  not  renewed.  It  was  found  that  the 
strongest  man  could  not  remain  under  water  longer  than  an  hour ;  but 
the  ill  effects  experienced  were  attributed  to  the  heat  which  accumu- 
lated in  the  bell,  and  which  was  supposed  to  affect  respiration.  Sub- 
sequently, when  an  apparatus  was  added  for  supplying  fresh  air,  it 
was  remarked  that  the  workmen  felt  no  inconvenience  whatever. 

The  first  observations  of  real  value  upon  the  effects  of  high  at- 
mospheric pressm-e  were  made  at  Howth,  near  Dublin,  in  the  year  1820, 
by  a  distinguished  Russian  physician  named  Hamel.  In  the  course  of 
some  engineering  work  in  which  diving-bells  were  employed,  Dr. 
Hamel  had  the  opportunity  of  studying  the  effects  of  compressed  air, 
not  only  upon  the  workmen,  but  also  upon  himself.  In  describing  his 
own  experience,  he  states  that  at  the  depth  of  five  or  six  feet  severe 
pain  was  felt  in  the  ears,  which  was  relieved  in  a  measure  by  swal- 
lowing. At  fifteen  or  sixteen  feet,  there  was  a  noise  in  the  ears  like 
an  explosion,  followed  by  entire  relief  from  the  pain.  His  respiration 
was  perfectly  easy. 

The  ascent  was  accomplished  with  much  less  inconvenience  than 
the  descent. 

Hamel  states  that  one  of  the  workmen  became  so  accustomed  to 
the  air  of  the  bell  as  to  be  uncomfortable  under  the  usual  atmospheric 
pressure.* 


*  Bibliotheque  ile  Geneve,  1820. 


5 


In  1826,  Dr.  Colladon  published  observations  made  at  the  same 
time  and  place  as  the  above.  In  winter  the  hours  of  work  in  the 
bells  were  five  daily  ;  in  summer,  five  and  ten  alternatel}^  Toward 
the  close  of  the  work,  each  day  the  men  became  very  much  exhausted, 
and  were  given  a  little  brandy  and  a  bit  of  bread.  Those  newly  em- 
ployed suffered  with  pain  in  the  head  and  ears,  and  were  often 
affected  with  colic  and  diarrhoea,  wiiich  last  were  attributed  to  cold 
and  wet.  Increase  of  appetite  and  augmentation  of  the  urine  were 
observed.  In  some  cases,  deafness  was  relieved,  and  one  case  of 
asthma  was  entirely  cured. 

In  1835,  Junod  published  the  results  of  extensive  experiments  upon 
compressed  air  as  a  remedial  agent.  *  This  was  the  beginning  of  a 
series  of  memoirs  upon  this  subject  appearing  in  rapid  succession  in 
France  and  Germany.  Institutions  sprang  up  in  various  parts  of  the 
Continent  designed  to  afford  the  most  approved  facilities  for  this 
mode  of  treatment,  and  the  results  obtained  w^re,  and  continue  to 
be,  highly  satisfactory.  The  "compressed  air-baths"  are  especially 
useful  in  the  treatment  of  pulmonary  diseases  and  of  dyspepsia. 

But  as  the  pressure  employed  in  these  baths  is  comparativel}^  slight, 
usually  not  more  than  eight  or  ten  pounds  to  the  square  inch,  the 
effects  observed  differ  widely  from  those  produced  by  the  high  pres- 
sure employed  for  engineering  purposes.  This  difference  is  not  only 
in  degree,  but  also  in  kind,  and  therefore  the  literature  relating  to 
compressed  ah*  as  a  remedy,t  although  rich,  and  in  itself  very  in- 
teresting, throws  but  little  light  upon  the  subject  of  this  discussion. 
It  is  probable,  however,  that  the  investigations  in  this  direction  of 
Junot,  Tabai^e,  and  Pravaz  first  suggested  the  employment  of  com- 
pressed air  as  a  substitute  for  pumps  in  mining  operations. 

To  M.  Triger,  a  French  engineer,  belongs  the  credit  of  first  con- 
ceiving and  carrying  out  a  plan  by  wiiich  atmospheric  pressure  was 
made  to  keep  back  the  water  flowing  into  a  mining  shaft.  It  had 
long  been  known  that  the  valley  of  the  Loire  was  underlaid  by  an  ex- 
tensive bed  of  coal,  but,  inasmuch  as  in  order  to  reach  the  coal  it 
was  necessary  to  pass  through  twenty  metres  of  quicksand  in  commu- 
nication with  the  water  of  the  river,  the  engineering  difficulties  had 
been  considered,  until  the  advent  of  Triger,  as  insurmountable.  To 
keep  a  shaft  dry  by  pumping  w^as  equivalent  to  pumping  out  the 
Loire.  .  To  meet  this  difficulty,  Triger  conceived  the  idea  of  sinking 
an  iron  tube  through  the  quicksand,  the  interior  of  the  tube  being 
kept  free  from  water  during  the  excavation  b}--  condensing  the  air  in 

*  Archives  Generales  de  Medicine. 

t  Those  interested  in  this  subject  will  find  it  exhaustively  treated  in  an  admira- 
ble work  by  Dr.  Rudolf  v.  Vivenot :  "  Zur  Erkenntniss  der  Physiologischen  Wir- 
kung  und  der  Therapeutischen  Anwendung  der  Verdichteten  Luft."  Erlangen, 
May,  1ST2. 


(> 


the  tube  to  the  point  of  counterbalancing  the  pressure  of  the  water. 
After  some  preliminary  experiments  made  by  the  aid  of  Tabarie's 
remedial  bath,  the  work  was  begun  in  1839,  near  Chalonnes,  A  tube 
of  iron,  seventy  feet  long  by  three  and  one-half  feet  in  diameter,  was 
provided,  with  a  box  or  chamber  at  the  top,  such  as  we  now  call  an 
air  lock,  having  a  valve  above  opening  inward,  and  another  below 
opening  downw^ard  into  the  tube.  These  valves  were  of  such  a  size 
as  to  permit  the  passage  of  the  workmen,  and  the  removal  of  the  ex- 
cavated material.  The  workmen  having  passed  into  the  lock,  the 
upper  valve  was  closed,  and  a  cock  opened  communicating  with  the 
main  tube,  where  the  air  was  compressed  sufficiently  to  keep  back 
the  water,  the  compression  being  effected  by  means  of  condensers 
worked  by  steam.  The  pressure  in  the  lock  having  become  equal  to 
that  in  the  main  tube,  the  lower  valve  Avas  opened  and  the  workmen 
descended  into  the  tube.  In  going  out,  or  in  sending  out  material,  the 
process  was  reversed.  The  tube  was  forced  down  into  the  earth  in 
proportion  as  the  wwkmen  excavated  at  the  bottom. 

It  will  thus  be  seen  that  the  first  attempt  at  this  mode  of  working 
embraced  all  the  essential  features  of  the  method  as  now  employed. 

In  his  undertaking,  Triger  w^as  completely  successful.  The  quick- 
sand was  passed  and  the  coal  reached,  and  at  the  same  time  there  was 
given  to  the  world  a  new  engineering  resource  of  exceeding  value. 

It  is  much  to  be  regretted  that  these  operations  were  not  carried  on 
under  the  eye  of  a  competent  medical  observer.  The  onl}^  report  we 
have  of  them  is  by  M.  Triger  himself,*  and  it  is  natural  that  the  en- 
gineering rather  than  the  medical  aspect  of  the  question  should  prin- 
cipally engage  his  attention.  His  notice  of  the  effects  of  the  com- 
pressed air  upon  the  workmen  is  extremely  meagre,  and  is  summed 
up  in  the  following  points  : 

"1.  At  the  pressure  of  three  atmospheres  it  is  impossible  to  whis- 
tle, Avhile  a  lower  pressure  does  not  produce  this  effect. 

"2.  In  the  compressed  air,  every  one  speaks  through  the  nose,  and 
this  is  the  more  noticeable  the  higher  the  pressure. 

"  3.  All  the  laborers  remarked  that  in  ascending  the  ladders  they 
were  much  less  out  of  breath  {moins  essouffles)  than  when  mounting 
to  a  similar  height  in  the  open  air. 

"  4.  A  laborer  who  had  been  deaf  since  the  seige  of  Antwerp, 
(1832,)  always  heard  mere  distinctly  in  the  compressed  air  than  any 
of  his  comrades. 

"No  illness  was  occasioned  among  the  laborers  except  that  two  of 
them,  after  seven  hours  of  labor  in  the  tube,  experienced  severe  pains 


*  Comptes  Renclues.  T.  XIII.  1S41.  "Memoire  sur  nn  appareil  d  air  com- 
prine  pour  le  ijercement  des  pnits,  etc.   Par  M.  Triger. 


i 

ill  the  arms  and  knees,  coming  on  about  half  an  hour  after  ascending 
into  the  open  air."  These  are  the  first  recorded  cases  of  what  I  have 
named  the  Caisson  Disease. 

About  the  year  1850  compressed  air  was  first  employed  in  the 
sinking  of  piers.  A  railway  bridge  was  constructed  over  the  Medway, 
between  Rochester  and  Chatham,  the  piers  of  which  rested  on  a  basis 
composed  of  hollow  iron  piles,  fortj'-two  inches  in  diameter,  each  of 
which  was  sunk  in  precisely  the  same  manner  as  the  tube  of  Triger. 
I  have  not  been  able  to  find  any  record  of  the  effects  of  the  com- 
pressed air  upon  the  men  employed,  though  some  accidents  due  to 
this  cause  are  stated  to  have  occurred. 

The  results  obtained  by  Triger  led,  in  1845,  to  the  application  of 
the  same  principle  to  the  working  of  the  mine  at  Douchy,  Depart- 
ment du  Nord.  The  laborers  in  this  case  were  under  the  supervision 
of  MM.  B.  Pol  and  T.  J.  J.  Watelle,  who  published  an  extremel}^  in- 
teresting memoir  upon  the  subject.* 

The  entire  personnel  comprised  sixt3'-four  men,  who  were  employed 
at  two  different  epochs,  under  different  pressures.  They  were 
divided  into  gangs  of  six  or  seven  each,  laboring  alternately  four 
hours  twice  a  day.  At  first,  the  time  allowed  for  locking  out  wa^s 
one-fourth  of  an  hour,  but  as  the  pressure  increased  it  wa^s  extended 
to  half  an  hour.  The  maximum  pressure  was  three  and  one-half 
atmospheres. 

After  each  shift  the  men  bathed  and  put  on  dry  clothes,  when  a 
cup  of  bouillon  and  a  glass  of  Bordeaux  were  served  to  each  man. 

As  the  number  of  cases  of  illness  increased,  a  sort  of  amhulance,  or 
temporary  hQ#pital,  was  established  at  the  spot. 

At  a  pressure  of  two  and  three-quarter  atmospheres,  Pol  experi- 
enced in  his  own  person  the  pain  in  the  ears  while  lockmg  in,  and  the 
ease  with  wliicli  a  ladder  is  ascended  in  the  compressed  air,  confirm- 
ing in  this  latter  pai'ticular  the  observation  of  Triger.  The  soot  from 
the  candles  with  which  the  an*  of  the  shaft  was  loaded,  produced  a 
troublesome  cough,  attended  with  black  expectoration.  The  mucous 
membrane  of  the  nose  and  throat  became  stained  with  it,  and  even 
the  faeces  were  blackened. 

While  locking  out  there  was  experienced  by  all  the  men  a  feeling 
of  suffocation.  Pol  was  the  first  to  perceive  that  the  real  danger  was 
in  passing  from  the  condensed  into  the  normal  atmosphere,  instead  of 
in  passing  in  the  reverse  direction.  On  emerging  into  the  open  air, 
he  found  that  his  pulse,  which  had  fallen  while  in  the  caisson  from 
seventy,  its  normal  standard,  to  fifty -five,  rose  suddenly  to  eighty- 
five.    When  the  pressure  had  increased  to  three  and  one-half  at- 


*  Memoire  sur  les  EfTets  de  la  Compression  de  Pair,  etc.  Annales  d'  Hygiene 
Publique  et  de  Med .    Legale,  1854. 


8 


mospheres,  he  again  entered  the  caisson.  The  unpleasant  sensations 
already  referred  to  were  found  to  be  intensified.  In  blowing  his  nose 
he  accidentally  discovered  that  this  operation  gave  much  more  perfect 
relief  to  the  ears  than  the  act  of  SAvalloM'ing.  In  speaking  he  found 
that  the  tongue  moved  stiffly  and  with  difficulty.  Sounds  were  not 
heard  with,  their  usual  intensity.  The  secretion  of  urine  Avas  decid- 
edly increased.  After  reaching  home  he  was  seized  with  severe  pain 
in  one  arm  and  shoulder,  and  in  the  walls  of  the  chest.  Afterward, 
there  were  chills,  followed  by  vomiting.  Rest  in  the  horizontal  po- 
sition, and  the  use  of  sudorifics,  restored  him  to  his  usual  health  by 
the  following  day. 

Of  the  sixty-four  men  employed,  thirty-nine  continued  until  the 
work  was  completed,  and  twenty-five  were  compelled  to  give  up  their 
places,  not  being  able  to  support  the  effects  of  the  compressed  air. 

The  most  usual  affection  was  muscular  pains,  occurring  either  alone 
or  ushering  in  other  symptoms.  Pulmonary  congestion  occurred  in 
several  cases,  but  it  may  well  be  questioned  whether  the  excessive 
impurity  of  the  air,  as  evinced  by  the  amount  of  soot  it  contained, 
may  not  have  had  much  to  do  with  the  production  of  this  otherwise 
unusual  result.  Other  s;>^nptoms  which  he  describes,  such  as  great 
hebitude,  incoherence  of  speech,  tottering  gait,  etc.,  indicate  the 
effects  of  carbonic  acid,  and  as  no  mention  is  made  of  any  provision 
for  removing  the  products  of  combustion  and  respiration,  this  gas 
must  have  been  present  in  considerable  quantity. 

The  conclusions  arrived  at  by  Pol  are  as  follows  : 

1.  A  pressure  of  four  and  one-quarter  atmospheres  is  not  in  itself 
dangerous,  but  the  return  into  the  open  air  may  cause  serious  acci- 
dents, and  even  sudden  death.  The  danger  is  in  proportion  to  the 
previous  pressure. 

2.  The  pathological  changes  consist  in  visceral  congestions,  among 
which  congestion  of  the  lungs  and  brain  take  the  foremost  rank. 

3.  The  tendency  to  these  congestions  increases  with  the  age,  at 
least  between  eighteen  and  fifty-five. 

4.  Not  the  period  of  greatest  strength,  which  is  between  thirty  and 
forty,  but  that  betAveen  eighteen  and  twenty-six  is  that  which  is  ex- 
posed to  the  least  danger. 

5.  Experience  teaches  that  the  ill  effects  are  in  proportion  to  the 
rapidity  ^^dth  Avhich  the  transition  is  made  from  the  compressed  air  to 
the  normal  atmosphere. 

6.  Unimportant  troubles,  such  as  cough,  gastric  symptoms,  etc., 
may  be  due  to  the  smoke  from  the  lamps. 

7.  The  treatment  is  not  different  from  that  which  is  usual  wh(  n 
like  symptoms  arise  from  other  causes.    The  first  indication  is  to 


9 


bring  about  a  reaction,  wliich  is  iu  turn  to  be  conibatted  Avhcn  it  ex- 
ceeds physiological  limits. 

8.  One  case  seems  to  indicate  that  the  quickest  and  safest  means  of 
restoration  is  an  immediate  return  into  the  compressed  ah. 

9.  Cold  to  the  surface  is  the  best  means  for  restoring  the  function  of 
the  skin. 

About  the  year  1856  this  metliod  of  excavation  was  employed  in 
the  coal  mines  at  Eischweiler,  near  Aix-le-Chapelle.  Xo  phenomena 
were  observed  differing  from  those  already  described,  except  that 
bleeding  from  the  nose  occurred  in  several  cases  on  emerging  into 
the  open  au\* 

About  18o8-9  excavation  by  the  aid  of  compressed  air  was  exten- 
sively employed  in  laying  the  foundations  of  piers  for  bridges. 
Among  the  first  of  these  were  the  Quarantine  Bridge  at  Lyons,  the 
bridge  at  Macon,  and  the  chain  bridge  over  the  Thiess.  A  report 
upon  the  latter  is  contained  in  the  Aunales  des  Fonts  et  des  Chaus- 
ses,"  for  1859.  Ringing  and  pain  in  the  ears  were  complained  of  by 
the  laborers,  as  also  pain  in  the  teeth,  and  in  the  muscles  generally. 
The  sound  of  the  voice  was  observed  to  be  changed,  and  the  breath- 
ing to  be  quickened.  The  return  to  the  open  ah*  was  often  followed 
by  bleeding  at  the  nose.  Men  of  several  different  nationalities  were 
employed,  and  it  was  observed  that  the  Hungarians  and  the  French 
suffered  least,  while  the  Italians.  Germans,  and  Sclavouians  were 
most  affected. 

In  1859.  the  mines  at  Eischweiler  were  re-opened,  compressed  air 
being  again  Anplo3Td.  The  pressure  did  not  exceed  two  and  one- 
half  atmospheres.  The  dm-ation  of  the  sliifts  was  six  hours.  Exces- 
sive s^veating  was  observed,  followed  by  thirst  after  leaving  the  mine. 
There  was  generally  impairment  of  appetite.  + 

At  the  same  time  work  was  being  carried  on  by  similar  means  in 
the  coal  mines  at  Liittich.  According  to  the  statement  of  the  super- 
intendent, the  men  became  so  emaciated  that  after  a  few  months  they 
could  no  longer  be  prevailed  upon  to  continue  the  work,  notT\ith- 
standing  large  wages  were  offered  and  the  most  nourishing  food 
provided. 

Perhaps  the  most  extensive  work  undertaken  in  Europe  by  the  aid 
of  compressed  air  was  the  bridge  over  the  Rhine,  at  Strasburg.  An 
accomit  of  this  is  given  by  Dr.  Francois,  who  had  medical  charge  of 
the  workmen.  J 

*  Vivenot.   Wirkimg  der  Verdichteten  Luft. 
t  Ibid. 

t  •*  Des  effets  sur  les  ouvriers  travaillant  dans  les  caissons  servants  de  base  anx 
piles  du  Pont  du  Grand  Khin."  Annales  d'  Hygiene  Publique  et  de  Med.  Legale. 
T.  XIV.  1860. 


10 


The  caissons  were  fourteen  in  number,  eacli  seven  metres  long  by 
five  and  eight-tenths  wide  and  three  and  five-tenths  high.  The 
locks  were  two  metres  in  diameter  and  four  metres  in  height. 

Francois  refers  to  the  progressive  impairment  of  hearing  as  the 
pressure  increased  in  the  lock  ;  to  the  increase  of  temperature  from 
the  compK'Ssion  of  the  ah- ;  and  to  the  accumulation  of  soot  in  the 
air-passages,  Avhich  had  been  before  observed  by  other  writers.  On 
going  out  of  the  caissons,  intense  pain  in  the  ears  sometimes  occurred, 
together  Avith  muscular  and  arthritic  pains.  A  very  annoying  itching 
of  the  skin  was  sometimes  felt.  Cerebral  congestions,  hcemoptysis, 
and  bleeding  at  the  nose,  were  also  not  uncommon.  Sometimes  these 
various  affections  occm-red  immediately  upon  leaving  the  caisson, 
while  in  other  cases  they  were  deferred  for  several  hours.  In  two  or 
three  instances  the  men  were  able  to  walk  home,  and  afterward  fell 
"  as  if  struck  by  lightning."  The  attacks  usually  passed  off  quickly. 
Only  one  death  occurred,  and  that  resulted  from  breaking  the  rule  as 
to  the  length  of  time  to  be  occupied  in  locking  out. 

The  rule  established  was  to  allow  from  four  to  five  minutes  in 
locking  out  when  the  pressure  was  one-quarter  to  one-half  an  at- 
mosphere ;  six  to  seven  minutes  for  one  atmosphere  ;  ten  for  one  and 
one-half  atmospheres ;  twel¥e  for  two  atmospheres.  A  woolen  vest 
was  provided  for  each  man  to  be  put  on  when  leaving  the  caisson,  in 
order  to  guard  against  the  effect  of  the  sudden  reduction  of  tempera- 
ture which  resulted  from  the  expansion  of  the  air  in  the  lock.  It  was 
observed  that  the  foremen  suffered  much  less  than  the  laborers,  since 
their  superior  intelligence  enabled  them  to  realize  the  necessity  of 
observing  the  rules. 

Some  other  points  observed  by  this  writer  will  be  referred  to  here- 
after in  their  proper  connection. 

In  the  year  1863,  Dr.  Antoine  Ed.  Foley  published  a  monograph 
comprising  his  observations  upon  the  effects  of  condensed  air  as 
demonstrated  dm-ing  the  sinking  of  the  piers  for  a  bridge  at  Argen- 
teuil.*  The  original  work  not  being  accessible,  I  avail  myself  of  the 
resume  contained  in  the  treatise  of  Vivenot,  of  which  I  give  a  some- 
what condensed  translation  from  the  German. 

Foley  observes  that  during  the  time  that  the  pressure  was  increas- 
ing, the  organs  of  hearing  were  alwaj's,  without  exception,  afifccted. 
Occasionally  neuralgic  pains  were  felt  darting  through  the  forehead, 
the  nasal  cavities,  and  the  jaws ;  the  voice  acquired  a  metallic 
sound ;  whistling  became  impossible  ;  in  a  few  cases  stammering  was 
induced.  Taste,  smell,  and  the  sense  of  touch  lost  their  acuteness. 
There  was  experienced  a  sense  of  warmth  in  the  skin,  as  if  one  were 


*"Du  travail  dans  s'air  comprime,  etude  medicale,  hygienique  et  biologique 
faite  au  pont  d'Argenteuil."  Paris,  1863. 


11 


in  a  dryiug-room.  The  pulse  became  small  and  thready,  sometimes 
imperceptible  to  the  touch.    The  venous  blood  had  a  bright  red  hue. 

The  lungs  seemed  to  increase  in  development,  while  the  motion  of 
the  ribs  was  less.  Shortness  of  breath  was  not  often  observed.  In- 
crease of  appetite  was  soon  experienced,  but  never  thirst. 

While  the  pressure  remained  stationary,  all  subjective  phenomena 
disappeared,  to  return  again  during  the  locking  out.  Ringing  of  the 
ears  and  bulging  of  the  ear  drums  were  observed  ;  taste  and  smell  re- 
turned ;  a  prickling  sense  of  warmth  was  felt  in  the  nostrils,  which 
was  sometimes  followed  by  bleeding  at  the  nose.  At  the  same  time 
the  rapid  decline  of  the  temperature  from  the  expansion  of  the  air 
caused  extreme  chilliness. 

At  first  the  laborers  remained  in  the  compressed  air  four  hours  at  a 
time,  twice  a  day,  with  an  interval  of  rest.  But  as  the  pressure  in- 
creased it  was  found  necessary  to  diminish  the  hours  of  labor. 

The  ill  effects  upon  the  workmen  were  almost  entirely  confined  to 
a  distressing  itching  of  the  skin  and  painful  congestive  swelling  of 
the  muscles.  They  observed  that  the  appetite  was  increased  while 
thirst  was  diminished.  The  flow  of  urine  was  also  greater  than 
usual. 

A  remarkable  case  is  mentioned,  in  which  a  man,  far  advanced  in 
consumption,  with  an  enormous  cavity  in  one  lung,  and  suffering 
from  hectic,  persisted  in  working  in  the  caisson,  contrary  to  the 
advice  of  Foley,  and  at  the  end  of  two  months  had  gained  ver}^ 
much  in  flesh,  was  looking  well,  and  feeling  in  the  best  of  health. 

I  shall  hav^  occasion  hereafter,  when  treating  of  the  Caisson  Dis- 
ease, to  refer  more  in  detail  to  some  of  the  experiences  of  this  writer. 

In  the  year  1868  there  was  begun  at  St.  Louis  a  work  which 
involved  the  application  of  compressed  air  on  a  scale  far  exceeding 
anything  before  attempted.  This  was  the  sinking  of  two  piers  and 
two  abutments  for  a  bridge  across  the  Mississippi.  The  magnitude 
of  the  work  consisted  in  the  great  depth  to  which  it  was  necessary  to 
sink  the  caissons,  in  order  to  obtain  a  solid  foundation.  One  of  them, 
at  the  moment  when  it  touched  the  rock,  was  110  feet  below  the 
surface  of  the  water.  This  implied  a  pressure  within  the  caisson  of 
50  lbs.  to  the  square  inch.  The  dimensions  of  the  caissons,  too,  far 
exceeded  those  of  any  before  constructed,  the  average  superficial 
area  being  about  3,700  square  feet. 

A  large  number  of  workmen  were  employed,  and  an  opportunity 
was  presented  for  studying  the  effects  of  compressed  air  upon  the 
human  body  on  a  scale  which  dwarfed  all  former  experien  ces  into 
comparative  insignificance. 

The  physician  in  charge  was  Dr  A.  Jaminet,  whose  report  is 
extremely  interesting.*    It  describes  a  number  of  valuable  experi- 


*  Physical  Effects  of  Compressed  Air,   St.  Louis,  1871, 


12 


ments  upon  the  boiling  point  of  water  at  various  pressures,  electri- 
cal phenomena,  etc.,  and  proceeds  to  detail  the  physiological  action 
of  high  atmospheric  pressure  as  demonstrated  upon  himself  and 
others.  The  writer  then  gives  his  own  experience  in  an  attack  of 
paralysis  resulting  from  a  prolonged  sojourn  in  the  caisson— a  paraly- 
sis from  which  he  fortunately  recovered  by  the  following  day. 
•  He  next  discusses  the  mode  in  which  the  pressure  acts  to  bring 
about  the  morbid  phenomena  observed,  and  arrives  at  the  conclusion, 
which  the  facts  do  not  seem  to  me  to  warrant,  that  the  ill  effects 
are  simply  the  result  of  exhaustion  from  too  rapid  tissue-change, 
caused  by  the  absorption  of  an  excess  of  oxygen.  Following  out 
this  idea,  he  lays  down  a  plan  of  treatment  which  consists  simply  of 
rest  in  a  recumbent  position,  with  the  feet  elevated,  and  the  adminis- 
tration of  stimulants  and  nourishment. 

He  describes,  more  or  less  in  detail,  seventy-seven  cases,  in  eight  of 
which  death  took  place.  The  post-mortem  appearances  in  these  are 
described.  They  were  all  characterized  by  congestion  of  the  brain 
and  cord,  and  of  most  of  the  abdominal  viscera. 

Dr.  Jaminet's  observations  are  exceedingly  valuable  ;  but  some  of 
his  conclusions  seem  to  have  been  arrived  at  without  sufficient 
thought.  It  is  especially  to  t)e  regretted  that  his  theory  of  exhaus- 
tion, framed  at  the  outset,  prevented  the  trial  of  remedial  plans  other 
than  the  routine  administration  of  stimulants  and  beef -tea. 

The  facts  observed  by  Dr.  Jaminet  will  be  frequently  referred  to 
in  the  following  pages,  care  being  taken  to  give  him  credit  for  all  that 
had  not  been  anticipated  by  others. 


CHAPTER  SECOND. 

THE  NEW  YOKK  CAISSON. 

Before  the  St.  Louis  Bridge  was  projected,  a  much  more  gigantic 
work  had  been  inaugurated  at  New  York,  and  plans  and  specifica- 
tions had  been  adopted  which  anticipated  the  leading  features  of  the 
work  at  St.  Louis.  To  cross  a  stream  1,600  feet  in  width  with  a 
single  span  was  an  idea  never  before  entertained.  But  the  difiicul- 
ties  were  immensely  increased  by  the  fact  that  the  towers  to  support 
this  immense  structure  had  to  be  erected  under  circumstances  that 
rendered  the  usual  methods  for  sinking  piers  impracticable.  It  was, 
therefore,  determined  to  employ  the  method  by  compressed  air,  and 
caissons  were  constructed  having  the  horizontal  dimensions  of  the 
proposed  piers,  which,  on  the  New  York  side,  were  102  by  172  feet. 
Each  caisson  was  in  effect  a  wooden  box  turned  bottom  upward,  the 
interior  space  being  9  feet  high.  The  roof  of  the  New  York  caisson 
(bottom  of  the  box)  was  22  feet  thick,  of  solid  timber  bolted  to- 


13 


getlier,  and  was  supported  by  frames  riiuning  from  side  tu  side,  which 
frames,  together  with  the  edges  of  the  box,  were  to  sustain  the  vast 
superincumbent  weight,  aided  by  the  upward  pressure  of  the  con- 
densed air  within  the  caisson.  Tlie  area  of  the  structure  was  equal 
to  seven  building  lots  of  25x100  feet  each 

The  caissons  having  been  built  on  ways,  were  launched  in  the  same 
manner  as  a  ship,  and  were  towed  to  the  points  where  the  piers  were 
to  be  located.  Courses  of  granite  blocks  were  then  laid  upon  the  top 
of  the  caisson,  by  which  it  was  sunk  until  it  rested  upon  the  bed  of 
the  river.  Air  was  then  forced  into  the  chambers  beneath  by  means 
of  engines  upon  the  shore,  until  the  water  was  entirely  displaced, 
and  the  river-bed  left  dry.  The  pressure  was  maintained  at  this 
point,  the  engines  working  day  and  night.  The  workmen  obtained 
access  to  the  chamber  by  means  of  two  shafts  w^hich  extended  above 
the  surface  of  the  water.  At  the  bottom  of  each  shaft  were  two  air- 
locks, which  were  simply  ante-chambers  constructed  of  iron,  into 
which  the  men  entered  from  the  shaft,  and,  closing  an  air-tight  door 
behind  them,  admitted  the  compressed  air  from  the  caisson  by  means 
of  a  cock,  until  the  pressure  in  the  lock  reached  the  same  degree  as 
that  in  the  caisson,  when  a  communicating  door  was  opened,  and  the 
men  passed  into  the  chamber  below.  In  going  out,  the  process  was  re- 
versed, the  compressed  air  in  the  lock  being  allow^ed  to  blow  off 
through  a  cock  into  the  open  shaft.  The  control  of  these  cocks  was 
intrusted  to  men  detailed  exclusively  for  that  work,  and  upon  their 
proper  management  depended  ;^the  comfort,  if  not  the  life,  of  every 
one  in  the  loc^. 

By  a  very  ingenious  arrangement,  which  it  is  not  necessary  to  de- 
scribe here,  the  earth  excavated  from  beneath  the  caisson  was  car- 
ried up  to  the  surface  without  affording  opportunity  for  the  air  to  es- 
cape. In  this  way  the  earth  w^as  being  constantly  removed  from  un- 
derneath the  caisson,  and  the  vast  mass  settled  day  by  day  down 
through  the  gravel  and  quicksand,  which  formed  the  bed  of  the  river, 
until  at  a  depth  of  78  feet  on  the  New  York  side,  a  solid  foundation 
was  reached.  In  proportion  as  the  caisson  settled  the  masonry  upon 
it  was  built  up,  so  that  the  top  of  the  stone-work  was  alw^ays  above 
water.  When  a  solid  foundation  had  been  reached,  the  interior  of 
the  caisson  was  filled  with  concrete,  and  the  400,000  (?ubic  feet  of 
timber  was  left  buried  nearly  80  feet  below  the  surface,  Avhere,  prac- 
tically indestructible,  it  remains  as  the  foundation  of  the  tower. 

Of  course  the  pressure  of  air  required  to  keep  the  water  out  of  the 
caisson  increased  in  exact  proportion  to  the  depth.  Thus,  at  the 
beginning  of  the  work,  the  caisson  being  covered  by  forty  feet  of 
water,  the  pressure  was  about  eighteen  pounds  to  the  square  inch, 
while  at  the  close  of  the  Avork  it  stood  at  thirty-six  pounds. 


14 


The  air-locks  were  connected  with  tlie  surface  of  the  pier  b}^  means 
of  a  spiral  stairway  within  the  shaft.  Ascending  this  was  found  to 
be  exceedingly  fatiguing  as  the  depth  increased,  and  the  stair  in  one 
of  the  shafts  was  finally  replaced  by  a  steam  elevator. 

Looking  upon  it  merely  from  a  sanitary  point  of  view,  I  regard  it 
as  a  serious  mistake  to  have  placed  the  air-locks  at  the  bottom 
instead  of  at  the  top  of  the  shafts,  as  by  that  arrangement  the  men 
were  compelled  to  make  a  fatiguing  ascent  at  the  moment  when  the 
circulation  was  embarrassed  and  the  system  unstrung  by  the  sudden 
removal  of  the  pressure.  All  testimony  is  agreed  upon  the  ease,  on 
the  one  hand,  with  which  exertion  is  supported  while  in  the  com- 
pressed air,  and  upon  the  unfitness  of  the  system,  on  the  other  hand, 
to  bear  even  the  slightest  fatigue  during  the  period  immediately  fol- 
lowing the  change  to  the  normal  atmosphere.  These  considerations 
should  render  the  rule  invariable  that  the  air-lock  is  to  be  placed  at 
the  top  of  the  shaft,  unless  an  elevator  is  employed.  In  this  view  I 
am  sustained  by  all  the  engineers  connected  with  the  work. 

The  caisson  was  lighted  by  gas  supplied  by  means  of  a  force-pump. 
The  combustion  of  the  gas,  together  with  the  breathing  of  the  work- 
men, gave  rise  to  the  formation  of  a  large  quantity  of  carbonic  acid. 
It  soon  became  evident,  that  the  amount  of  air  which  was  required  to 
supply  the  leakage  and  keep  up  the  requisite  pressure  was  not  ade- 
quate to  maintain  a  healthy  standard  of  purity  in  the  air  respired. 
This  conclusion,  arrived  at  by  observation  and  calculation,  was  con- 
firmed by  trial.  A  rough,  but  satisfactory,  test  was  supplied  by  tak- 
ing a  bottle  of  lime-water  into  the  caisson  and  passing  the  air  through 
the  water  by  means  of  an  ordinary  flexible  rubber  syi'inge.  It  was 
found  that  a  few  compressions  of  the  bulb  were  suflicient  to  give  the 
water  a  decidedly  milky  hue.  This  method  has  the  advantage  over 
that  employed  by  Dr.  Jaminet,  viz. ,  merely  shaking  an  open  bottle 
containing  lime-water — that  it  constantly  brings  new  portions  of  air 
into  contact  with  the  fluid. 

By  increasing  the  number  of  compressors  by  which  the  air  was 
supplied,  (the  excess  of  air  escaping  beneath  the  edge  of  the  caisson,) 
the  atmosphere  was  brought  to  such  a  degree  of  purity  as  to  contain 
only  one-third  of  one  per  cent,  of  carbonic  acid,  as  I  determined  hy 
actual  analysis.  This  amount  of  vitiation  was  found  not  to  affect  the 
men  unfavorably.  To  maintain  this  standard,  however,  nearly 
150,000  cubic  feet  of  au*  were  required  per  hour. 

The  number  of  men  employed  at  one  time  in  the  caisson  varied 
from  fifty  to  one  hundred  and  twenty-five  in  the  day  time,  and  from 
fifteen  to  thirty  during  the  night.  At  first  the  time  was  divided  into 
two  "  shifts  "  of  four  hours  each,  separated  by  an  interval  of  two 
hours.    As  the  depth  increased  the  liours  were  reduced,  until  at  last 


15 


the  two  shifts  comprised  but  four  hours,  dividetl  by  a  four  hours" 
interval. 

It  was  not  until  the  pressiu'e  had  reached  about  twenty-four  pounds 
that  any  serious  effect  upon  the  men  ^vas  obseryed.  At  this  time  I 
began  my  daily  attendance  of  from  one  to  three  hours  at  the  bridge. 
The  first  step  was  to  prepare  a  set  of  printed  rules,  copies  of  which 
were  posted  conspicuously.    These  rules  were  as  follows  : 

1st. — Xeyer  enter  the  caisson  with  an  empty  stomach. 
2d. — Use  as  far  as  possible  a  meat  diet,  and  take  warm  coffee 
freely. 

od. — Always  put  on  extra  clothing  on  coming  out,  and  avoid  ex- 
posure to  cold. 

4th. — Exercise  as  little  as  maybe  during  the  first  hour  after  coming 
out,  and  lie  down  if  possible. 
5tli. — Use  intoxicating  liquors  spai'ingly  ;  better  not  at  all. 
6th. — Take  at  least  eight  hom's'  sleep  every  night. 
7th.— See  that  the  bowels  are  open  every  day. 
8th. — Xever  enter  the  caisson  if  at  all  sick. 

9th. — Report  at  once  at  the  office  all  cases  of  illness,  even  if  they 
occur  after  going  home. 

I  next  subjected  all  the  men  to  an  examination  intended  to  exclude 
all  who  were  suffering  from  heart  or  lung  disease,  and  those  en- 
feebled by  age  or  intemperance.  All  new  men  thereafter  were  re- 
quii-ed  to  pref ent  a  permit  signed  by  me  before  they  were  allowed  to 
enter  the  caisson.  Though  but  few  were  actually  rejected,  the 
knowledge  that  they  would  be  examined,  doubtless  deterred  many 
who  were  not  sound  from  applying  for  work.  The  personnel  was 
therefore  of  the  best,  as  it  then  appeared.  Subsequent  experience 
would,  however,  have  modified  my  choice  materially. 

On  my  recommendation  a  cup  of  good  coffee  was  served  to  each 
man  immediately  upon  leaving  the  caisson.  It  appeared  to  relieve, 
in  a  measure,  the  nervous  prostration  which  marked  the  return  to  the 
open  air  ;  and  possibl}^  \)y  the  effect  w^hich  coffee  is  known  to  have, 
it  may  have  done  something,  also,  to  check  the  tendency  to  too  rapid 
tissue-change. 

A  large  room  in  the  j'ard  was  fitted  up  with  bunks  and  benches, 
which  afforded  the  men  an  opportunity  of  resting  while  the  changes 
were  going  on  in  the  system  which  were  required  to  bring  it  into  its 
normal  condition  after  coming  up.  Connected  with  this  room  were 
conveniences  for  hot  and  cold  bathing,  and  also  lockers  in  which  each 
man  kept  a  change  of  dry  under-clothmg,  to  be  put  on  inmiediately 


10 


on  coming  up.  Each  man  was  supplied  by  the  company  with  a  pair 
of  long  rubber  boots,  which  were  rendered  necessary  by  the  work  re- 
quiring them  to  stand  more  or  less  in  the  water. 

The  physical  conditions  to  which  the  men  were  subjected  in  their 
work  were  very  peculiar.  In  the  first  place,  in  passing  through  the 
lock  in  going  dowm,  there  "was  a  very  sudden  rise  of  temperature  from 
the  condensation  of  the  air  This  rise  amounted  to  upwards  of  30" 
F.  in  many  cases,  and  not  infrequentl}^  when  the  outside  tempera- 
ture was  low,  to  50°  or  60°.  This  change  in  the  temperature  was 
coincident  with  an  increase  of  atmospheric  pressure  of  from  18  to 
36  lbs.  to  the  square  inch.  At  the  same  time  the  men  passed  from  an 
atmosphere  of  the  usual  dryness  to  one  saturated  or  super-saturated 
Avith  moisture.  The  labor  required  in  the  caisson  was  not  unusually 
severe.  After  from  two  to  four  hours  passed  in  the  compressed  air, 
the  men  repaired  to  the  locks,  where  in  the  space  of  from  seven  to 
fifteen  minutes  the  pressure  was  reduced  to  the  normal  standard. 
As  the  result  of  the  expansion  of  the  air  in  the  lock,  the  temperature 
fell  as  rapidly  as  it  rose  in  the  former  case.  This,  which  was  felt  to 
be  a  serious  inconvenience  in  the  Brooklyn  caisson,  was  remedied  on 
the  New  York  side  by  surrounding  the  interior  of  the  lock  with  coils 
of  pipe  heated  by  steam.  T)?e  steam  Avas  shut  off  at  all  times  except 
while  locking  out. 

The  moisture  of  the  atmosphere  of  the  caisson,  referred  to  above, 
was  caused  partly  by  the  ' '  water-packing  "  used  in  the  condensers 
which  supplied  the  air,  and  partly  by  the  water  with  which  the 
soil  underneath  the  caisson  was  saturated. 

From  the  25th  of  January,  1872,  when  I  assumed  medical  charge 
of  the  men,  until  the  31st  of  May,  when  I  resigned  the  position,  110 
cases  of  sickness  occm-red  which  were  fairly  due  to  the  compressed 
air,  and  were  of  sufficient  severity  to  come  under  treatment.  Of 
these,  three  proved  fatal. 

The  sick  were  treated  in  the  first  instance  at  the  yard,  where 
a  room  was  set  apart  as  a  temporary  hospital.  Cases  occurring  dur- 
ing ni}^  absence  were  treated  by  the  engineer  on  duty,  according  to 
a  specified  plan ;  or,  if  the  case  was  severe,  I  was  summoned. 
Serious  cases  were  ultimately  sent  to  the  public  hospitals  or  to  their 
homes. 

The  ages  of  the  men  ranged  from  18  to  50.  They  were  of  almost 
all  nationalities,  but  I  did  not  find  that  any  sensible  difference  in 
ability  to  bear  the  work  resulted  from  nativity,  as  observed  by  Pol. 

The  habits  of  many  of  the  men  were  doubtless  not  favorable  to 
health,  but  everything  which  admonition  could  do,  was  done  to 
restrain  them  from  excesses.  Many  of  them  slept  in  crow^ded  lodging- 
houses,  where  the  beds  or  bunks  were  arranged  in  tiers,  one  above 


17 


the  other  ;  iu  rooms  in  which  there  was  scarcely  an  attempt  at  venti- 
lation. One  of  them  fell  a  victim  to  spotted  fever,  contracted  from 
such  surroundings,  and  his  death  was  at  once  ascribed  by  his  com- 
rades to  the  effects  of  the  condensed  air. 

Serious  inconvenience  M'as  occasioned  to  the  men  in  the  caisson  by 
the  large  amoimt  of  unconsumed  carbon  from  the  gas,  which  floated 
in  the  air  in  the  form  of  smoke.  The  inhalation  of  this  produced 
more  or  less  irritation  of  the  air-passages,  and  gave  rise  to  a  very 
characteristic  black  expectoration.  This  continued  for  an  astonish- 
ingly long  period  after  the  work  in  the  caisson  was  terminated.  At 
the  time  of  my  writing,  nearly  six  months  after  the  work  was  com- 
pleted, some  of  the  men  are  still  coughing  up  sputa,  streaked  with 
black.  Where  this  carbon  could  have  been  lodged  for  so  long  a 
period,  is  a  question  which  I  am  not  prepared  to  answer. 

The  smoking  of  the  gas  was  found  by  some  experiments  of  Mr. 
Collingwood,  one  of  the  engineers,  to  be  due  to  the  comparative 
immobility  of  the  compressed  air,  which  prevented  the  formation  of 
the  currents  necessary  to  bring  new  supplies  of  oxygen  to  the  flame. 
By  reducing  the  aperture  of  the  burners,  and  at  the  same  time  giving 
it  such  a  form  that  the  gas  escaped  in  a  thin  sheet,  a  relatively  great- 
er surface  was  secured  for  contact  with  the  air.  This  obviated  almost 
entirely  the  tendency  to  smoke,  and  added  also  to  the  illuminating 
power  of  the  gas. 

The  sinking  of  the  caisson  was  begun  on  the  13tli  of  December, 
1871,  and  the  filling  in  with  concrete  was  completed  on  the  20th  of 
July,  1872  :  the  duration  of  the  submarine  work  being  221  days. 

During  thia^eriod  I  was  in  the  habit  of  frequently  entering  the 
caisson,  remaining  from  one  to  two  hours  at  a  time.  Yet  in  my  case, 
with  the  exception  of  occasional  slight  pain  in  the  maxillary  sinuses, 
not  the  least  inconvenience  was  experienced. 


CHAPTER  THIRD. 

EFFECTS  OF  COMPRESSED  AIR. 

The  effects  of  a  highly  condensed  atmosphere  upon  the  sj^stem 
may  be  divided  into  those  which  are  physiological  or  consistent  with 
health,  and  those  which  are  pathological,  and  constitute  or  induce 
disease 

The  physiological  effects  will  be  considered  according  to  the  organs 
or  functions  in  which  they  are  exhibited. 

Effect  on  the  Hearing. — It  is  a  law  of  acoustics  that  within  the 
limits  of  mobility  the  denser  the  medium  through  which  the  sound 
waves  are  communicated,  the  larger  the  wave,  and  therefore  the 

B 


18 


louder  the  sound.  This  supposes,  of  course,  that  the  ear  itself  re- 
mains under  normal  conditions.  Such,  however,  is  not  the  case 
when  the  observer  is  in  a  highly  condensed  atmosphere.  The  un- 
usual pressure  upon  all  parts  of  the  auditory  apparatus  opposes  a 
mechanical  obstacle  to  the  freedom  of  vibration,  which  is  essential 
to  perfect  hearing  *  Hence,  although  larger  sound  waves  may  strike 
upon  the  ear-drum,  feebler  impressions  are  communicated  to  the 
auditory  nerve,  and  the  sound  appears  to  be  fainter  than  in  the  opeij 
air.  Thus,  by  repeated  experiments,  I  found  that  a  watch  that  could 
be  heard  distinctly  at  a  distance  of  18  inches  in  a  very  noisy  place  in 
the  open  air,  could  not  be  heard  at  a  greater  distance  than  two  inches 
in  the  comparative  silence  of  the  caisson. 

At  the  same  time  the  velocity  of  the  waves  of  sound  is  greater,  and 
hence  the  pitch  is  higher.  A  deep  bass  voice  is  changed  to  a  shrill 
treble,  and  the  prolonged,  heavy  sound  of  a  blast  is  so  modified  as  to 
resemble  the  sharp  report  of  a  pistol. 

This  modification  of  sound  is  very  striking,  and  is  almost  the  only 
thing  to  remind  the  casual  observer  that  he  is  moving  about  in  an 
atmosphere  three  or  four  times  as  dense  as  that  to  which  he  is  accus- 
tomed. 

A  curious  fact,  noticeable  under  these  circumstances,  and  one  which 
was  long  ago  obser^^ed  in  diving-bells,  is  that  it  is  impossible  to 
whistle.  The  utmost  effort  of  the  expiratory  muscles  is  not  suffi- 
cient to  increase  materially  the  density  of  the  air  in  the  cavity  ot  the 
mouth,  and  hence  on  its  escape  there  is  not  sufficient  expansion  to 
produce  a  musical  note.  A  similar  difficulty,  though  in  a  less  degree, 
is  experienced  in  speaking,  and  for  this  reason  protracted  conversa- 
tion is  very  fatiguing. 

Effect  upon  Respiration. — In  a  highly  compressed  air,  the  frequency 
of  the  respiration  is  increased.  Dr.  Jaminet  gives  the  rate  as  21  per 
minute,  with  a  pressure  of  33  lbs.,  which  accords  with  my  own  ob- 
servations. He  ascribes  this  increase  of  three  or  four  per  minute  to 
an  increased  absorption  of  oxygen.  Experiments  show,  however, 
that  simply  increasing  the  supply  of  oxygen,  the  frequency 

of  respiration  instead  of  increasing  it.  The  true  explanation,  I 
think,  is  to  be  found  in  the  fact  that  the  quantity  of  carbonic  acid 
held  in  solution  by  blood,  as  by  water,  is  in  proportion  to  the  pressure 
to  which  the  gas  is  subjected ;  and  hence  with  the  pressure  existing 
in  the  caisson,  the  elimination  of  carbonic  acid  from  the  blood  would 
not  be  as  perfect  as  under  normal  circumstances,  unless  the  air  in  the 
lungs  were  more  frequently  changed.  As  observed  by  Frangois  and 
Dr.  Jaminet,  the  depth  of  the  inspirations  is  also  increased.  With 

*  An  analogous  fact  was  observed  by  Foley,  viz.,  that  his  watch  invariably  lo>it 
time  when  taken  into  the  caisson,  thus  showing  that  the  movements  of  the  ))al- 
ance-wheel  were  less  free  in  the  compressed  than  in  the  normal  air. 


19 


the  view  of  appreciating  thie  amount  of  increase  of  the  respiratory 
movements,  as  well  in  amplitude  as  in  frequency,  I  devised  the  fol- 
lowing plan  :  By  a  very  simple  contrivance  attached  to  a  steel  band 
placed  around  the  chest,  a  measuring  tape  was  made  to  traverse  with 
each  inspiration  a  distance  corresponding  to  the  increase  in  the  cir- 
cumference of  the  chest.  The  aggregate  distance  traversed  in  a  given 
time  was  made  the  standard  of  comparison,  and  of  course  indicated 
the  combined  frequency  and  amplitude  of  the  respirations. 

A  number  of  trials  with  this  instrument  made  upon  myself  in  the 
open  air,  gave  a  very  uniform  result  of  1^  inches  of  tape  unwound 
every  two  minutes.  On  repeating  the  experiment  in  the  caisson 
under  a  pressure  of  33  lbs.,  2f  inches  were  unwound  in  the  same 
time. 

Bffect  upon  the  Circulation. — It  has  been  shown  by  numerous  ob- 
servers that  under  a  slightly  increased  pressure,  such  as  is  employed 
in  compressed  air-baths,  the  pulse  loses  in  frequency  from  the  first. 
Tills  is  doubtless  due  to  an  increased  absorption  of  oxygen  by  the 
blood,  which  thus  affords  a  sufficient  supply  to  the  tissues  without 
the  necessity  of  keeping  up  the  usual  activity  of  the  circulation.  In 
the  course  of  some  experiments  undertaken  nearly  four  years  ago,  I 
demonstrated  that  the  same  effect  results  under  a  normal  pressure 
from  adding  oxygen  to  the  air  inhaled.  But  as  the  pressure  in- 
creases, the  question  is  transferred  from  the  domain  of  chemistry  to 
that  of  mechanics.  The  condensation  of  the  tissues  from  the  pres- 
sure to  which  they  are  subjected,  and  the  consequent  narrowing  of 
the  vessels,  oppose  a  physical  obstacle  to  the  circulation,  which  is  felt 
before  the  blood  has  time  to  become  sm-charged  with  ox3^gen,  and 
while  there  is  still  a  necessity  for  an  active  cii-culatiou.  The  labor 
of  the  heart  is  thus  increased,  and  its  action,  in  consequence,  excited. 
I  have  frequently  seen  the  pulse  rise  to  120  immediately  upon  enter- 
ing the  caisson,  where  the  pressure  was  from  30  to  35  lbs.  to  the  inch. 

But  after  the  lapse  of  a  period  varying  in  different  cases  from  half 
an  hour  to  two  hours,  the  pulse  falls  back  to  its  normal  standard,  or 
even,  it  maybe,  below  it.*  The  blood  has  now  become  saturated 
with  oxygen,  and  consequently  a  less  active  circulation  is  demanded. 

Doubtless,  if  the  pressure  were  very  gradually  admitted,  the  pre- 
liminary rise  in  the  pulse  would  not  take  place,  the  favorable  chemi- 
cal action  keeping  in  advance  of  and  counteracting  the  unfavorable 
mechanical  conditions. 

The  effect  of  high  atmospheric  pressure  upon  the  volume  of  the 
pulse  is  always,  according  to  my  observation,  to  diminish  it.  This  is 
easily  accounted  for  by  the  pressure  exerted  upon  the  arterj',  which 
prevents  its  yielding  readily  to  the  expanding  force  of  each  successive 


*  My  experience  in  tliis  corresponds  precisely  with  that  of  Dr.  Jaminet. 


20 


wave  of  blood.  Hence  the  pulse  is  small,  hard,  and  wiry.  These 
characteristics  are  independent  in  a  great  degree  of  the  frequency  of 
the  beat,  although  as  the  heart  recovers  from  the  irritable  con- 
dition into  which  it  is  thrown  by  the  sudden  increase  of  the  pressure, 
and  settles  down,  so  to  speak,  more  calmly  to  its  work,  it  contracts 
with  more  force,  and  the  pulse  gains  somewhat  in  volume.  These 
changes  in  both  the  frequency  and  fullness  of  the  pulse  are  well  shown 
in  the  annexed  tracings,  taken  in  the  Brooklyn  caisson.  The  upper 
line  represents  in  each  case  the  normal  pulse,  the  lower  line  that  in 
the  compressed  air. 


The  difference  in  the  readiness  with  which  the  process  of  adapta- 
tion to  an  increased  pressure  is  accomplished  in  different  persons  is 
shown  by  the  pulse-rate  of  eleven  men  taken  an  hour  and  a  half  after 
going  into  the  caisson  when  the  pressure  was  thirty-five  pounds.  The 
figures  are  arranged  in  the  order  of  frequency. 

116—116—106—104—96—92—88—76—74—68—52. 
These  figures  give  an  average  of  ninety.  On  another  occasion,  with 
a  pressure  of  thirty-two  pounds,  and  a  sojourn  in  the  caisson  of  two 
and  a  half  hours,  the  average  was  eighty.  Whether  a  longer  expo- 
sure to  the  same  jn-essure  would  have  produced  a  further  decline  in 
the  frequency  of  the  i)ulse  is  a  question  which  the  hours  for  working 
did  not  allow  me  to  determine. 


21 


It  is  remarkable  that  the  wide  variations  in  the  pulse-rate  above 
mentioned  were  not  accompanied  by  any  symptoms  appreciable  to 
the  individual.  A  man  with  a  pulse  of  fifty-two,  and  another  with 
one  of  one  hundred  aftd  sixteen,  felt  equally  well,  and  each  was  en- 
tirely unconscious  of  anything  unusual  in  the  heart's  action. 

The  effect  of  the  pressiu'e  upon  the  cutaneous  vessels  is  shown  by 
the  pallor  of  the  face,  Avhich  is  very  marked,  and  continues  for  fif- 
teen or  twenty  minutes  after  leaving  the  caisson.  The  hands,  too, 
feel  shrunken,  and  the  palmai*  surface  of  the  fingers  is  often  shriv- 
elled, as  if  soaked  in  water.  The  pressure  acting  upon  all  sides  of  the 
fingers  empties  them  to  a  considerable  extent  of  blood,  rendering  the 
skin  apparently  too  large  for  them.  The  veins,  too,  on  the  back  of 
the  hand  seem  to  be  effaced. 

This  absence  of  blood  from  the  surface  implies  necessarily  an  ex- 
cess in  the  interior  of  the  body,  where  the  effect  of  the  pressure  is  not 
as  great.  This  point  will  come  up  again  in  considering  the  pathology 
of  the  Caisson  Disease. 

Effect  upon  Tem-perature.  —In  none  of  the  reports  upon  the  effects 
of  high  pressure  as  employed  for  engineering  purposes,  have  I  been 
able  to  find  any  records  of  temperature.  J.  Lange,*  however,  found 
that  under  the  comparatively  slight  pressure  which  is  used  as  a  reme- 
dy, the  temperature  of  the  body  suffered  a  slight  decrease.  This  is, 
no  doubt,  due  to  an  increased  absorption  of  oxygen,  which  has  been 
shown  by  Mr.  Savory  and  also  by  experiments  of  my  own  to  produce 
this  effect. 

During  tl^e  work  in  the  New  York  caisson  when  the  pressure  was 
about  32  l6s. ,  I  took  the  temperature  of  seven  of  the  men  an  hour 
and  a  half  after  entering  the  caisson,  and  found  that  it  averaged 
99.6®  F.,  exactly  one  degree  above  the  normal  standard.  At  first  I  ac- 
cepted this  as  the  result  of  the  increased  interstitial  change  so  strong- 
ly insisted  upon  b}'  Dr.  Jaminet,  but  subsequent  observation  led  me 
to  interpret  it  differently. 

The  temperature  of  the  body  in  health  is  kept  at  about  98.6°  F.,  by 
the  constant  evaporation  from  the  surface.  But  in  the  caisson,  as 
already  mentioned,  the  air  was  always  nearly  or  quite  saturated  with 
moisture,  so  that  evaporation  from  the  surface  must  have  been  prac- 
tically suspended.  With  the  temperature  of  the  air  at  76'',  as  it  was 
at  the  time  of  the  observations,  and  the  men  engaged  in  severe  labor, 
it  is  easy  to  see  how  the  absence  of  the  cooling  process  of  evapora- 
tion from  the  surface  would  lead  to  a  rise  of  one  degree  of  the  ther- 
mometer. This  view  is  strengthened  by  the  result  of  three  observa- 
tions on  a  subsequent  occasion,  when  the  temperature  in  the  caisson 
stood  at  81®,  instead  of  76".    The  average  in  this  instance  Avas  101®. 


*  Vivenot. 


22 


A  rise  of  tive  degrees  in  the  temperature  of  tlie  air  could  not  sensibly 
affect  the  rapidity  of  tissue-change,  but  if  not  counteracted  by  evap- 
oration from  the  skin,  it  would  soon  tell  upon  the  temperature  of  the 
body. 

The  influence  of  the  hygrometric  condition  of  the  atmosphere 
upon  the  temperature  of  the  body  is  a  matter  of  daily  observation. 
On  a  clear,  dry  day,  with  a  high  barometer,  we  are  surprised  to  find 
the  thermometer  indicating  a  temperature  much  higher  than  our  sen- 
sations would  lead  us  to  expect,  while  on  the  contrary,  on  a  cloudy 
day,  with  a  low  barometer,  we  can  scarcely  persuade  ourselves  that 
the  temperature  is  not  many  degrees  higher  than  the  thermometer  in- 
dicates. In  the  dry,  clear  air  of  New  Mexico  I  have  supported  a  tem- 
perature of  110°,  without  inconvenience,  while  in  the  humid  atmos- 
phere of  the  Florida  Keys  I  have  found  it  almost  unbearable  at  86''. 

Effect  upon  the  Perspiratory  Function. — Several  writers  have  ob- 
served that  it  is  immediately  remarked  by  every  one  entering  a 
caisson  that  the  secretion  from  the  skin  is  apparently  immensely 
increased.  It  is  noticeable  even  when  the  temperature  of  the  air  is 
moderate,  but  as  this  increases  it  becomes  a  very  serious  annoyance. 
The  clothing  quickly  becomes  saturated,  which,  besides  the  discom- 
fort it  occasions,  exposes  to  gieat  danger  of  taking  cold  on  going  out 
into  the  open  air. 

But  a  little  examination  served  to  show  me  that  in  the  New  York 
caisson,  at  least,  there  was  really  no  increase  of  the  secretion  from  the 
skin,  but  that,  instead  of  evaporating,  the  moisture  accumulated  upon 
the  surface,  and  thus  simulated  excessive  sweating.  This  was  owing 
to  the  moist  condition  of  the  atmosphere  already  mentioned,  which 
rendered  the  drying  of  the  surface  by  evaporation  impossible.  The 
atmosphere  possessed  to  an  extreme  degree  the  quality  of  "  niuggi- 
ness,"  and  the  apparently  profuse  perspiration  was  merely  an  exag- 
geration of  what  we  suffer  from  in  very  damp  weather,  even  though 
the  temperature  be  not  extreme. 

So  far  from  the  perspiratory  glands  being  stimulated  by  the  density 
of  the  atmosphere,  it  is  probable  that  the  anaemia  of  the  skin  already 
described,  as  resulting  from  the  pressure  upon  the  surface,  would 
tend  to  lessen  the  secretion  by  diminishing  the  supply  of  blood  to  the 
glands. 

That  there  is  not  an  imdue  amount  of  fluid  carried  off  thi'ougli  the 
skin,  is  shown  by  the  absence  of  thirst  so  generally  remarked. 

The  foregoing  explanation  of  the  apparent  increase  of  perspiration 
is  important,  as  it  bears  upon  the  theory  of  excessive  waste  of  tissue, 
in  which  the  perspiration  is  supposed  to  aid. 

Effect  upon  Digestion. — Nearly  all  authors  who  have  written  upon 
the  effects  of  compressed  air  agree  in  stating  that  for  a  time,  at  least, 


23 


it  increases  the  appetite  to  a  remarkable  extent.  Indeed  this  is  one 
of  the  first  and  most  favorable  results  observed  where  compressed  air 
is  applied  remedially.  With  this  experience  my  own  observations  in 
the  main  agree.  It  was  frequently  remarked  by  the  men  working  in 
the  New  York  caisson  that  their  work  made  them  unusually  hungry, 
that  they  "  could  not  get  enough  to  eat,"  etc.  Of  course,  it  was  not 
possible  to  obtain  any  exact  data  as  to  the  relative  amount  of  food 
consumed,  but  from  careful  inquiries  I  arrived  at  the  conclusion  that 
it  was  considerably  in  excess  of  Avhat  is  usual  in  the  case  of  men 
engaged  in  similar  labor  in  the  open  air.  Still,  there  were  many 
exceptions  to  the  general  rule,  especially  among  those  Avho  had  been 
long  engaged  upon  the  work,  and  whose  general  tone  was  beginning 
to  deteriorate.  Among  these,  loss  of  appetite  Avas  often  complained  of. 

The  fact  of  this  generally  increased  appetite  seems  to  point  to  an 
increased  Avaste  of  tissue,  to  be  supplied  by  a  greater  consumption  of 
food.  An  increased  absorption  of  oxygen  such  as  Ave  assume  to  take 
place,  seems  from  the  observations  of  several  authorities*  to  imply 
greater  activity  of  tissue-change  as  the  ultimate  result.  But  in  this 
case  I  think  it  is  scarcely  safe  to  accept  this  explanation  at  once  as 
conclusive  and  sufficient.  It  may  aa^cII  be  questioned  whether  during 
the  actual  sojourn  in  the  caisson  the  functions  of  digestion,  absorp- 
tion, and  assimilation  proceed  normally  under  the  wide  departure  of 
the  system  from  its  natural  conditions.  If  it  could  be  shoAA'n  that  a 
considerable  portion  of  the  food  taken  before  entering  the  caisson  is 
but  imperfectly  digested  or  assimilated,  the  subsequent  hunger  Avould 
be  readily  accounted  for.  I  am  not  aware  that  this  point  has  ever 
been  investigated,  but  I  can  scarcely  believe  that  such  an  increase  of 
appetite  as  is  described  could  depend  Avholly  upon  increased  inter- 
stitial change  without  giving  rise  to  marked  elevation  of  temperature 
and  other  SA'mptoms  denoting  unusual  chemical  activity.  On  the 
contrary,  I  think  it  highly  probable  that  an  examination  of  the  de- 
jecta would  shoAv  them  not  to  be  entirely  exhausted  of  nutritious 
material.  At  all  events,  until  this  point  is  subjected  to  rigid  tests,  it 
Avill  be  unsafe  to  regard  the  amount  of  food  consumed  as  a  measure 
of  the  metamorphosis  of  tissue. 

If  the  metamorphosis  of  tissue  is  really  greatly  accelerated  through 
the  influence  of  compressed  air,  it  should  be  apparent  in  a  more 
prompt  healing  of  Avounds.  The  folloAving  experiment  Avas  intended 
to  test  this  point : 

Four  pigeons  Avere  selected,  as  much  alike  as  possible  in  size  and 
vigor.  Under  the  Aving  of  each  a  Avound  Avas  made  by  removing  a 
circular  piece  of  the  integument  about  half  an  inch  in  diameter. 
Two  of  the  pigeons  AA^ere  then  sent  down  into  the  caisson,  the  other 
*  "  New  York  ;Nreflical  Journal."  April,  1870. 


24 


two  being  retained  in  the  hospital  on  the  wharf.  The  conditions  in 
other  respects  were  the  same.  At  the  end  of  six  days  the  wounds  in 
the  two  below  were  perfectly  healed.  Of  the  two  above,  in  one  the 
wound  was  perfectly  healed,  while  in  the  other  it  was  still  covered 
by  a  scab,  which  fell  off  two  or  three  days  later. 

The  result  of  this  experiment  w^ould  not  indicate  any  considerable 
difference  in  the  activity  of  the  vital  processes.  I  may  remark  that 
the  w^orkmen  never  spoke  of  the  wounds  or  injuries  they  received  as 
healing  more  rapidly  than  when  working  in  the  external  air. 

Effect  npon  the  Urinary  Secretion. — Dr.  Jaminet,  in  his  observa- 
tions at  St.  Louis,  found  that  the  amount  of  fluid  secreted  by  the 
kidneys  was  very  much  increased,  in  some  instances  nearly  doubled, 
while  the  specific  gravity  was  but  little,  if  at  all,  below  the  usual 
average.  This  shows  that  the  solid  matter  excreted  was  also  in  much 
greater  quantity  than  usual.*  But  I  cannot  agree  with  him  in  attrib- 
uting this  exclusively  to  the  excessive  waste  of  tissue  from  over-oxyd- 
ation  of  the  blood.  The  explanation  is  to  be  found,  I  think,  chiefly 
in  the  fact  that  the  skin,  as  already  stated,  performs  its  function 
very  imperfectly,  owing  to  the  impossibility  of  evaporation  from  the 
surface  when  the  air  is  already  loaded  with  moisture,  and  hence  a 
portion  of  its  duty  is  forced  ^ipon  the  kidneys,  organs  always  ready 
to  act  vicariously  for  the  skin  or  the  mucous  surfaces. 

Furthermore,  the  excretion  of  a  large  amount  of  urea  indicates  a 
relatively  deficient  oxydation  of  tissue,  and  is  one  of  the  characteris- 
tics of  those  diseases  in  which  respiration  is  suddenly  embarrassed, 
as,  for  instance,  pneumonia. 

Another  circumstance  not  to  be  lost  sight  of,  is  that  the  pressure 
upon  the  surface  acts  mechanically  to  congest  all  the  abdominal  vis- 
cera, and  that  congestion  of  the  kidneys,  within  physiological  limits, 
produces  increased  secretion  of  urine. 

From  w^hat  precedes  it  will  be  inferred  that  I  am  not  willing  to  ac- 
cept the  view  which  practically  sets  no  limit  to  the  amount  of  oxygen 
that  the  system  will  appropriate  in  a  sufficiently  condensed  atmos- 
phere. Even  if  absorbed  by  the  blood,  it  does  not  follow  that,  the 
excess  of  oxygen  is  received  into  the  normal  vital  relations  with  the 
tissues.  It  may  be  held  in  simple  compulsory  solution  in  the  blood, 
as  in  any  other  liquid  ;  it  may  even  give  rise  to  chemical  changes  in 
the  blood,  and  solid  tissues  as  in  dead  matter,  and  thus  act  as  a  poison, 
as  asserted  by  M.  Bert,t  but  we  have  no  w^arrant  for  believing  that  it 
so  acts  as  to  cause  the  removal  of  particles  not  yet  eifete,  and  which 
but  for  this  would  have  remained  normal  active  constituents  of  the 

*  These  oV)servations  accord  with  those  of  Foley,  J.  Lange,  Pol,  Pravaz,  and 
others, 
t  L'Institut,  July  i?,  1872 


25 


body.  Behind  mere  chemical  action  lies  a  vital  principle  in  accord- 
ance with  which  each  molecule  is  born,  as  it  were,  into  the  economy, 
reaches  maturity,  performs  its  function,  becomes  effete,  and  is  suc- 
ceeded by  a  new  molecule ;  and  to  break  in  upon  this  order  is  to 
strike  at  the  very  essence  of  life. 

I  do  not  intend  by  this  to  deny  that  an  atmosphere  highly  oxygen- 
ated, either  by  the  addition  of  oxygen  or  by  compression,  is  capable 
of  accelerating  the  vital  processes  within  certain  limits.  I  only 
contend  that  these  limits  correspond  with  the  extreme  limit  of 
physiological  demand — that  the  capacity  of  the  system  to  appropriate 
and  use  oxygen  has  a  definite  relation  to  the  possible  wants  of  the 
system  under  natural  conditions.  For  a  contingency  beyond  these, 
nature  has  made  no  provision. 


CHAPTER  FOURTH. 

PATHOLOGICAL  EFFECTS. 

The  pathological  effects  of  high  atmospheric  pressure  comprise 
certain  phenomena  easily  explained  upon  mechanical  principles,  and 
in  addition  to  these,  a  group  of  symptoms,  having  a  definite  relation 
to  each  other,  and  constituting  a  specific  affection,  which,  from  the 
peculiarity  of  its  origin,  I  propose  to  call  the  Caisson  Disease. 

The  affections,  which  are  of  a  purely  mechanical  nature,  relate  to 
the  cavities  communicating  with  the  nasal  passages,  such  as  the  ears 
and  the  fronlal  and  maxillary  sinuses,  etc. 

Affections  of  the  ears  are  mentioned  by  nearlj'  every  writer  on  the 
subject  of  compressed  air,  and  are  extremely  common.  They 
depend,  for  the  most  pai't,  upon  closure  of  the  Eustachian  tubes,  by 
which  communication  of  the  cavity  of  the  middle  ear  with  the 
external  air  is  cut  off.  The  men  under  my  charge  Avere  warned  most 
strenuously  not  to  go  into  the  lock  unless  they  were  able,  when 
holding  the  nose  and  blowing  forcibly,  to  feel  the  air  enter  both 
ears,  thus  insuring  that  the  tubes  were  per\ious.  Nevertheless,  cases 
often  occurred  in  which  this  precaution  was  neglected,  and  the  indi- 
vidual was,  as  a  consequence,  "  caught  in  the  lock,"  unable  to 

change  his  ears. "  This  inability  to  equalize  the  pressure  upon  the 
two  sides  of  the  ear-drum,  caused  extreme  pain,  and  sometimes 
entailed  serious  results.  The  effect  is  two-fold.  The  pressure  upon 
the  outside  of  the  drum  being  greater  than  upon  the  inside,  the  mem- 
brane is  pressed  inward  with  a  force,  which,  if  it  does  not  produce  a 
rupture,  at  least  causes  a  degree  of  tension  which  so  delicate  an 
organ  as  the  ear  is  not  fitted  to  bear  \\ith  impunity,  and  which  may 
be  the  starting  point  of  an  acute  inflammation.    (See  Case  I.,  p.  43.) 

4 


26 


But  the  pressure  may  be  so  great  as  to  rupture  the  drum  at  once,  as 
in  Case  II.,  p.  43. 

When  there  is  continued  exposure  to  the  effect  of  compressed  air, 
with  closure  of  the  Eustachian  tube,  the  structures  within  the  cavity 
of  tlie  tympanum  not  being  acted  upon  by  the  increased  pressure,  are 
placed  relatively  in  the  same  position  as  the  skin  under  a  cupping- 
glass,  and  the  sama  result  follows,  viz.,  intense  congestion,  which 
may,  in  this  case,  lead  to  inflammation.  Indeed,  the  difference 
in  pressure  within  and  without  is  much  greater  than  in  the  case 
of  the  cupping-glass,  since  in  the  latter  it  cannot  exceed  one  at- 
mosphere, while  in  the  former  it  may  be  two  or  three  atmospheres. 

The  stoppage  of  the  Eustachian  tube  may  very  frequently  be  over- 
come by  forcing  in  air  through  the  nose  after  the  method  described 
by  Politzer.  In  this  way  a  great  many  of  the  men  under  my  care 
were  enabled  to  continue  their  work,  who  otherwise  could  not  have 
done  so,  without  incurring  serious  risk.  This  simple  operation  was 
constantly  called  into  requisition,  as  many  as  four  or  live  of  the  men 
sometimes  presenting  themselves  in  the  course  of  my  visit  to  have 
their  "  ears  blown  out,"  and  it  rarely  happened  that  they  experienced 
any  difficulty  afterward  on  entering  the  lock.* 

Three  cases  of  extreme  deafness  came  under  my  notice,  two  of 
them  in  laborers,  and  one  in  the  person  of  a  gentleman,  who  was  ad- 
vised by  a  physician  to  visit  the  caisson  with  the  hope  that  he  might 
receive  benefit  from  the  action  of  the  compressed  air.  In  all  these 
cases  the  hearing  was  very  much  improved  while  in  the  caisson,  but 
on  returning  to  the  open  air  the  former  degree  of  deafness  immedi- 
ately returned. 

A  number  of  cases  of  otities  are  mentioned  by  Frangois,  as  occur- 
ring under  his  observation  during  the  sinking  of  the  caissons  at  Stras- 
burg.f  His  favorite  remedy  Avas  oil  of  jasmine  dropped  into  the 
ear.  He  also  employed  leeches  and  fomentations.  He  condemns 
catheterism  of  the  tubes,  on  theoretical  grounds,  while  admitting 
that  he  had  never  employed  it. 

Pain,  more  or  less  severe,  in  the  frontal  or  maxillary  sinuses  was 
sometimes  experienced.  This  w^as  doubtless  caused  by  a  temporary 
closure  of  the  passage  leading  to  the  nasal  cavity.  In  one  case,  in 
which  the  frontal  sinus  was  affected,  the  pain,  though  not  severe, 
was  very  persistent,  continuing  for  several  days. 

In  one  case  pain  in  the  frontal  sinus  was  felt  as  the  pressure  was 
increasing  in  the  lock,  and  again,  and  more  severely,  as  the  pressure 
was  reduced  in  returning  to  the  open  air.  This  latter  pain  was  ac- 
companied by  a  discharge  of  bloody  mucous  from  the  nose.  In  this 
case  there  was  doubtless  closure  of  the  passage  into  the  sinus,  thus 

•  I  am  under  obligations  to  Dr.  Roosa  for  valuable  hints  in  reference  to  the  treat- 
ment of  these  cases, 
t  See  page  9. 


27 


preventin<^  the  equalization  of  the  pressure,  and  giving  rise  to  the 
pain  first  felt.  There  resulted  also  congestion  of  the  lining  mem- 
brane, followed  by  an  increased  flow  of  mucous  and  extravasation  of 
blood.  But  in  the  course  of  the  two  hours  passed  in  the  caisson,  the 
air  gradually  filtered  through  the  obstruction,  and  when  the  outside 
pressure  was  removed,  the  air  thus  imprisoned  forced  a  way  out,  car- 
rying before  it  the  mucous  and  blood  that  had  accumulated  in  the 
sinus.    (See  Case  IV.,  p.  43.) 

It  becomes  an  interestmg  question  what  degree  of  condensation  of 
this  atmosphere  will  prove  directly  fatal.  Dr.  Richardson,  of  Lon- 
don, told  me  recently  that  he  had  experimented  largely  upon  this 
subject,  and  that  for  the  small  animals  which  he  had  employed,  such 
as  rabbits,  cats,  dogs,  etc. ,  the  limit  of  endurance  seemed  to  be  be- 
tween six  and  seven  atmospheres.  He  found,  however,  that  the  re- 
sult varied  widely,  with  comparatively  slight  variations  of  tempera- 
ture, such  as  would  have  no  appreciable  effect  upon  vitality  under 
other  conditions. 


CHAPTER  FIFTH. 

THE  CAISSON  DISEASE. 

Definition. — A  disease  depending  upon  increased  atmospJieric  pres- 
sure, hut  always  developed  after  the  pressure  is  removed.  It  is  charac- 
terized hy  extreme  pain  in  one  or  more  of  the  extremities,  and  sometimes 
in  the  trunk,  and  which  may  or  may  not  be  associated  icith  epigastric 
pain  and  vomiting.  In  some  cases  the  pain  is  accompanied  by  paralysis 
more  or  less*  complete,  lohich  may  be  general  or  local,  but  is  most  fre- 
quently confined  to  the  lower  half  of  the  body.  Cerebral  symptoms, 
such  as  headache  and  vertigo,  are  sometimes  present.  The  above  symp- 
toms are  connected,  at  least  in  the  fatal  cases,  loith  congestion  of  the 
brain  and  spinal  cord,  often  resulting  in  serous  or  sanguineous  effusion, 
and  icith  congestion  of  most  of  the  abdominal  viscera. 

SYMPTOMS. 

Neuralgic  Pains. — These  constitute  in  general  the  first  and  most 
characteristic  symptoms,  and  are  very  seldom  absent.  The  accession 
is  often  very  abrupt,  as  if  the  patient  "had  been  struck  by  a 
bullet."  At  other  times  the  pain  is  slight  at  first,  but  rapidly  increases 
in  intensity.  In  well-marked  cases  the  suffering  is  extreme,  men  of 
%  the  strongest  nerve  being  completely  subdued  by  it.    It  is  "  as  if  the 

flesh  were  being  torn  from  the  bones."  The  pain  is  usually  of  a 
remittent  or  paroxysmal  character,  the  exacerbations  occurring  at 
short  intervals,  especially  if  the  patient  attempt  to  move.  Though 
usually  designated  as  "cramps,"  these  pains  are  rarely  accompanied 
by  muscular  spasms.    They  generally  begin  in  one  or  both  of  the 


28 


knees,  shifting  to  the  legs  or  thighs,  and  then  perhaps  creeping  up 
along  the  trunk  to  seize  upon  the  shoulders  and  arms.  Not  unfre- 
quently  the  severest  pain  is  felt  in  the  spine,  and  especially  in  the 
lumbar  portion.  There  is  usually  some  degree  of  tenderness  with  the 
pain,  so  that  the  patient  will  complain  if  friction  be  applied  too 
vigorously.  There  is  also  a  painful  stiifness  in  the  affected  limbs, 
that  precludes  motion  in  the  absence  of  actual  paralysis. 

In  some  cases,  there  are  swelling  and  heat  as  well  as  tenderness, 
indicating  engorgement  of  the  tissues,  and  this  may  persist  for  seve- 
ral days,  being  followed  occasionally  by  discoloration,  as  if  from  a 
bruise.    (Case  VII.,  p.  44.) 

Frangois  mentions  a  case  in  which  the  engorgement  was  followed 
by  suppuration.  In  two  of  my  cases,  minute  spots  of  extravasated 
blood  in  the  substance  of  the  skin  at  the  seat  of  pain,  gave  the  sur- 
face the  appearance  of  being  spattered  with  red  ink.  (Case  XI., 
p.  45.) 

A  curious  case  of  the  swelling  of  the  mammary  gland  recurring- 
each  day  is  given  among  the  Illustrative  Cases,  No.  IX.  FrauQoia 
relates  a  similar  instance. 

The  Pulse. — At  the  outset  of  the  attack  the  pulse  will  differ 
according  to  the  time  which  has  elapsed  since  leaving  the  caisson, 
being,  as  a  rule,  quicker  and  more  frequent  in  proportion  as  the  time 
is  shorter.  Dr.  Jaminet  observed  that  if  the  attack  occurred  imr.e- 
diately  after  coming  up,  the  pulse  usually  ranged  from  95  to  115, 
while,  if  it  were  delayed  for  half  an  hour,  the  pulse  would  be 
slow — perhaps  as  low  as  60. 

But  as  these  rates  do  not  differ  from  those  in  healthy  persons  at 
the  same  periods  after  leaving  the  caisson,  they  do  not  possess  any 
special  significance  in  those  taken  sick. 

The  subsequent  character  of  the  pulse  is  simply  indicative  of  the 
general  condition  of  the  patient. 

The  Skin  is  usually  cool  at  first,  often  of  a  slightly  leaden  hue,  and 
nearly  always  covered  with  a  profuse  cold  perspiration,  standing  out 
in  beads  upon  the  surface.  This  perspiration  is  very  characteristic. 
At  first  I  supposed  it  to  be  owing  to  the  excessive  pain  which  the  pa- 
tient was  suffering  ;  but  subsequently  it  occurred  in  several  cases  in 
which  the  pain  was  slight  or  entirely  absent.  (See  Case  VI.)  I  was, 
therefore,  inclined  to  attribute  it  to  a  relaxation  of  the  cutaneous 
capillaries  through  some  nervous  agency  analagous  in  its  action  t<> 
what  we  see  in  cases  of  extreme  terror,  and  having  its  origin  in  the 
general  disturbance  of  the  nervous  system  which  chai-acterizes  the 
disease. 

In  several  instances  in  which  I  ascertained  the  temperature  in  the 
axilla,  it  was  found  to  be  normal. 


29 


Epigastric  Pain  and  Vomiting. — Pain  at  the  pit  of  the  stomach, 
usually,  but  not  always,  attended  by  vomiting,  is  of  frequent  occur- 
rence. It  occurred  in  24  per  cent,  of  my  cases.  This  is  a  much 
smaller  percentage  than  that  observed  by  Dr.  Jaminet,  who  found 
the  gastric  symptoms  to  be  present  in  66  out  of  77  cases.  This  may 
be  owing  to  the  pressure  being  greater  at  St.  Louis  than  at  New  York, 
nearly  all  of  Dr.  Jaminet's  cases  occurring  under  a  pressure  of  40 
lbs.  and  upward,  while  the  pressure  at  New  York  did  not  rise  above 
36  lbs. 

The  pain  in  the  epigastrium,  if  not  relieved  by  treatment,  is  gener- 
ally followed  within  a  brief  period  by  vomiting,  which  may  continue 
with  great  persistence  even  after  the  pain  has  ceased.  In  most  cases, 
however,  the  vomiting  is  limited  to  the  ejection  of  the  contents  of 
the  stomach. 

In  a  few  instances  I  observed  the  occurrence  of  vomiting  without 
the  usual  preceding  pain.  In  these  cases  there  was  also  dizziness,  in- 
dicating that  the  vomiting  was  of  cerebral  origin. 

Paralysis — This  occurred  to  a  greater  or  less  degree  in  47  out  of 
77  cases  observed  by  Dr.  Jaminet.  This  is  at  the  rate  of  61  per  cent. 
At  New  York  it  occurred  in  only  about  15  per  cent,  of  the  cases ; 
the  difference  being  due,  no  doubt,  to  the  difference  of  pressure. 
The  paralysis  affects  most  frequently  the  lower  half  of  the  body, 
but  it  may  include  the  trunk  or  one  or  both  arms.  In  rare  instances 
the  arms  alone  are  affected.  The  paralysis  usually  comes  on  a  short 
time  after  the  beginning  of  the  pains,  but  it  may  occur  where  there 
is  very  little  if  any  pain.  (Case  XXV.)  It  affects  sensation  as  well 
as  motion.  The  patient  does  not,  however,  obtain  relief  from  his 
suffering,  since  the  pain  in  the  limbs  will  continue  after  pain  from 
other  sources  is  no  longer  felt.  Thus  a  leg,  for  example,  may  be  en- 
tirely insensible  to  pricking  or  pinching,  while  at  the  same  time  it  is 
the  seat  of  extreme  suffering.  In  fact,  the  neuralgic  pain  and  the 
paralysis  seem  to  be  so  far  independent  of  each  other,  that  either 
may  exist  separately  as  well  as  both  together. 

The  degree  of  paralysis  may  vary  from  mere  weakness  of  the 
limbs,  with  slightly  impaired  sensation,  including  a  loss  of  "hold 
upon  the  ground  "  in  walking,  to  complete  loss  of  motion  and  sensa- 
tion in  the  affected  part.  Even  the  minor  degrees  generally  involve 
the  bladder,  and  in  two  or  three  of  my  cases  the  paralysis,  after  the 
first  day  or  two,  was  confined  to  this  organ. 

Cerebral  Symptoms. — Symptoms  of  a  transient  character  are  often 
observed,  which  have  their  origin  in  the  brain.  They  consist  of 
headache,  dizziness,  double  vision,  incoherence  of  speech,  and  some- 
times unconsciousness,  the  last  from  syncope.  They  are  usually  of 
very  short  duration,  passing  off  in  a  few  hours.    In  the  fatal  cases. 


30 


however,  a  condition  of  profound  coma  is  the  usual  forerunner  of 
death.  The  occurrence  of  this  symptom  leaves  but  little  hope  of  the 
patient's  recovery. 

Prognosis. — The  duration  of  the  Caisson  Disease  varies  from  three 
or  four  hours  to  six  or  eight  days.  When  paralysis  takes  place,  this 
may  continue  for  weeks,  or  it  may  pass  off  within  twelve  hours. 
The  cases  marked  only  by  neuralgic  pains  do  not  generally  last  more 
than  twelve  hours,  though  some  continue  five  or  six  days. 

Death  occurs  only  in  cases  which  are  severe  from  the  first,  and  are 
marked  by  symptoms  of  serous  or  sanguineous  effusion  about  the 
brain  or  cord. 

Morbid  Anatomy. — The  constant  lesion  in  fatal  cases  of  Caisson 
Disease  is  congestion  of  the  brain  or  spinal  cord.  This  congestion 
may  be  evenly  distributed,  or  it  may  vary  in  intensity  in  different 
localities.  This  is  especially  true  as  regards  the  cord.  The  conges- 
tion affects  both  the  meninges  and  the  substance  of  the  brain  or 
cord.  In  some  instances  extravasation  of  blood  takes  place,  as  in 
Case  XXVI.,  chapter  6.  In  most  of  the  published  cases  there  was 
found  also  more  or  less  serous  effusion  in  the  arachnoid. 

The  tissues  of  the  scalp  and  those  surrounding  the  spinal  column 
are  sometimes  engorged.  Dr.  Jaminet  describes  a  case  in  which  the 
tissues  over  the  spine  were  congested,  the  vascularity  increasing 
regularly  as  the  dissection  proceeded  deeper  toward  the  vertebral 
column. 

When  sufficient  time  elapses  before  death,  there  may  be  softening 
of  the  brain,  occurring  in  spots.  This  is  probably  due  to  occlusion 
of  the  vessels  by  coagula  formed  during  the  primary  congestion. 

Congestions  also  occur  in  other  localities,  and  especially  in  the 
solid  abdominal  viscera.  The  liver  and  spleen  have  been  found 
engorged  in  nearly  every  case.  The  kidneys,  too,  are  usually  con- 
gested, and  in  several  cases  described  by  Dr.  Jaminet,  clots  of  blood 
were  found  extravasated  in  the  organ. 

The  mucous  membrane  of  the  stomach,  intestines,  and  bladder  is 
often  found  injected  and  marked  with  ecchymotic  patches. 

The  lungs,  in  cases  of  true  Caisson  Disease,  seldom  present  any 
other  change  than  simple  hypostatic  congestion. 

Pathology. — It  iB  probable  that  the  pathology  of  this  disease  is  not 
entirely  uniform  in  all  cases.  Doubtless,  the  chief  element  in  it  is 
the  congestions  already  described,  and  especially  of  the  brain  and 
spinal  cord.  The  mechanism,  therefore,  of  these  congestions,  be 
comes  a  subject  of  paramount  importance. 

It  is  obvious  that  if  the  blood  were  exposed  to  an  equal  pressure  in 
all  parts  of  the  body,  there  would  be  no  change  in  its  distribution. 


*  Physical  Effects  of  Compressed  Air.  P.  20. 


31 


It  is  equally  clear  tlint  the  blood,  if  free  to  move,  will  pass  from  a 
place  where  the  pressure  is  greater  to  one  where  it  is  less.  The 
body  is  made  up  of  structures  of  different  densities,  and  presenting  a 
varying  resistance  to  compression.  But  permeating  these  structures 
in  every  direction  are  vessels  in  perfect  communication  throughout 
the  entire  system,  and  filled  with  a  mobile  fluid,  which  is  free  to 
change  its  locality  in  obedience  to  any  force  which  is  brought  to  act 
upon  it.  Now,  w^hen  the  surface  of  the  body  is  subjected  to  an 
even  pressure  on  all  sides,  the  tendency  is  to  a  distribution  of  this 
pressure  toward  the  centre.  If  the  body  were  composed  entirely  of 
solids,  this  could  be  effected  only  by  the  compression  of  those  solids, 
and  a  point  w^ould  very  soon  be  reached  where  the  resistance  w^ould 
balance  the  compressing  force,  and  the  parts  lying  more  toward  the 
centre  w^ould  remain  unaffected.  But  the  presence  of  a  fluid  in  the 
structures,  with  free  channels  in  w^hich  to  move,  changes  all  this. 
While  the  solid  tissue  resists  compression,  the  fluid  blood  retreats 
from  the  surface  to  the  centre,  and  accumulates  there  until  an  equi- 
librium of  pressure  is  produced. 

Hence  we  deduce  the  law,  that  under  high  atmospheric  pressure 
the  centres  will  be  congested  at  the  expense  of  the  periphery. 

But,  aside  from  location,  vessels  coursing  through  dense  and  resist- 
ing organs,  will  be  less  exposed  to  external  pressure  than  those  pass- 
ing through  soft  and  yielding  structures.  Hence  a  second  law%  that 
firm  and  compact  structures  will  be  congested  at  the  expense  of  those 
more  compressible. 

But  ther^  are  structures  very  soft  and  yielding  in  themselves,  yet 
enveloped  'in  a  rigid  casing  of  bone  which  entirely  shuts  off  the  influ- 
ence of  external  pressure.  Hence  the  establishment  of  the  equilib- 
rium in  them  is  wholly  dependent  upon  an  afflux  of  blood.  This 
gives  us  the  third  law,  that  structures  w  ithin  closed  bony  cavities 
are  congested  at  the  expense  of  all  others. 

In  accordance  with  these  laws,  we  shall  find  that  while  in  the  cais- 
son, the  condition  of  the  different  parts  in  regard  to  the  supplj^  of 
blood  w  ill  be  as  follows  : 

The  skin  and  the  superficial  structures  will  be  antemic*  The  cen- 
tral portion  of  the  limbs  and  the  interior  organs  of  the  body  w  ill  be 
congested.  The  solid  viscera  of  the  abdomen  will  be  especially  en- 
gorged on  account  of  both  situation  and  structure.  The  brain  and 
spinal  cord,  and  the  interior  of  the  shaft  of  the  long  bones,  will  be 
congested  to  a  high  degree  from  the  operation  of  the  third  law. 

These  changes  are  not  perfected  until  a  considerable  time  has  been 
passed  in  the  compressed  air.  The  circulation  up  to  this  point  goes 
on  everywhere  with  vigor,  the  change  being  in  the  relative  calibre  of 


*  This  is  shown  by  the  pallor  which  is  very  characteristic.  See  p.  21. 


32 


the  vessels,  not  in  their  tension.  The  counter-pressure  becomes  uni- 
form throughout  the  \i  hole  vascular  system,  but  this  counter-pres- 
sure supersedes  the  natural  muscular  resistance  or  tone  of  the  vessels, 
which  have  become  passive  tubes.  The  blood  is  distributed  not  in 
accordance  with  the  physiological  demands  of  the  different  parts,  but 
in  obedience  to  overpowering  physical  force. 

This  is  the  condition  of  the  circulation  at  the  moment  that  the  pro- 
cess of  locking  out  begins.  Yet  the  changes  which  have  taken  place 
up  to  this  point  are  not  the  cause  of  the  morbid  phenomena  which 
constitute  the  Caisson  Disease,  else  the  attack  would  take  place  while 
in  the  compressed  air,  instead  of  after  leaving  it.  It  is  evident  that 
the  removal  of  the  pressure,  and  not  the  pressure  itself,  is  the  immedi- 
ate cause  of  the  seizure. 

This  removal  is  effected  in  the  few  minutes  which  are  occupied  in 
locking  out.  But  it  is  not  to  be  supposed  that  the  vessels  will  in- 
stantly assume  their  normal  condition.  They  are  in  a  state  of  relax- 
ation, not  only  in  the  congested,  but  also  in  the  anaemic  parts ;  in  the 
former,  because  of  over-distension — in  the  latter,  because  the  muscu- 
lar coat  cannot  at  once  recover  from  its  inaction.  The  aggregate 
capacity  of  the  vascular  system  will,  therefore,  be  in  excess,  com- 
pared to  the  volume  of  blood  to  be  conveyed ;  or,  in  other  words,  there 
will  be  a  lowering  of  vascular  tension. 

Hence,  the  circulation  will  be  languid,  and  the  congested  parts  w'U 
not  readily  empty  themselves  of  the  excess  of  blood  which  they  con- 
tain. Especially  will  this  be  the  case  in  the  brain  and  spinal  cord, 
where  the  conditions  are  most  favorable  for  the  production  of  con- 
gestion. The  capillaries  being  clogged  with  eifete  blood,  the  nutri- 
tion of  the  part  nmst  suffer,  and  disturbance  of  function  will  result. 

It  is  to  this,  I  think,  that  the  delirium,  and  the  transient  loss  of 
consciousness,  which  occasionally  occur,  are  to  be  attributed.  When 
the  spinal  cord  is  the  seat  of  this  condition,  pain  in  the  parts  deriving 
their  nerves  from  that  section  of  the  cord  may  result,  or  paralysis 
more  or  less  complete  may  follow. 

This  appears  to  me  to  account  for  the  phenomena  in  those  cases  in 
which  the  local  symptom  is  paralysis  or  pain  of  a  transient  or  shifting 
character.  These  cases  may,  I  think,  be  considered  as  entirely  spinal 
in  their  origin.  But  in  many  cases  there  are  evident  local  changes 
such  as  tumefaction,  rise  of  temperature,  etc.,  which  indicate  local 
irritation,  and  which  are  probably  due  to  obstruction  of  the  vessels 
of  the  part  as  a  sequel  to  the  local  congestion.  This  explanation  is 
applicable  also  to  those  cases  in  which  the  pain  is  fixed  in  one  locality, 
which  may  be  very  much  circumscribed,  and  where  it  persists  for 
days  without  intermission,  feeling,  as  the  patient  expresses  it,  "  as  if 
it  were  in  the  bone,"  where  it  very  likely  is.    Such  a  pain  presents  a 


33 


marked  contrast  to  those  shifting  pains  which  have  been  described, 
and  if  considered  of  spinal  origin,  would  indicate  a  serious  lesion  con- 
lined  to  a  minute  portion  of  the  cord.  That  such  a  circumscribed 
lesion  might  occur  as  a  very  rare  exception,  must  be  admitted  ;  but 
that  it  should  be  present  in  a  considerable  proportion  of  cases  is  in 
the  last  degree  improbable. 

The  testimony  of  all  observers  is,  that  the  liability  to  attack  is  di- 
rectly as  the  duration  of  the  stay  in  the  caisson.  This  admits  of  an 
easy  explanation  on  the  theory  which  I  have  advanced.  The  more 
thoroughly  the  system  has  become  adapted  to  the  change  in  the 
circulation,  the  less  readily  it  will  resume  its  normal  condition  when 
the  pressure  is  removed.  The  congested  vessels,  especially,  will  lose 
their  contractility  in  proportion  to  the  time  their  muscular  fibres  have 
been  upon  the  stretch. 

It  was  suggested  by  Francois,  that  the  morbid  phenomena  result- 
ing from  high  pressures  might  be  due  to  the  liberation  of  air  which 
had  been  absorbed  by  the  blood  while  under  pressure,  but  which  was 
set  free  again  when  the  pressure  was  removed. 

The  same  idea  has  since  been  advanced  by  Prof.  Rameaux,  of 
Strasburg. 

Within  the  past  year  M.  Paul  Bert  has  communicated  to  the 
French  Academy*  the  results  of  a  series  of  experiments  made  upon 
animals  with  very  high  pressui*es,  reaching  sometimes  to  19  at- 
mospheres. He  shows  that  when  death  is  the  direct  result  of  the  pres- 
sure it  is  induced  by  an  excessive  absorption  of  oxygen,  which  then 
enters  into  chemical  union  Avith  the  blood,  and  acts  as  a  poison.  He 
found  that  the  gas  w^hich  escapes  from  the  blood  after  the  pressure  is 
removed,  is  composed  of  a  mixture  of  nitrogen  and  carbonic  acid, 
with  scarcely  a  trace  of  oxygen,  the  oxygen  being  retained  by  the 
blood.  This  poisoning  by  oxygen,  however,  produces  its  effect  while 
in  the  compressed  air,  and  therefore  cannot  be  a  factor  in  the  pro- 
duction of  the  Caisson  Disease. 

But  M.  Bert  re-asserts  the  theory  of  Frangois  and  Prof.  Rameaux, 
with  this  difference  :  that  he  claims  that  bubbles  of  nitrogen  instead  of 
air  are  the  cause  of  the  interruption  of  the  circulation.  These  bub- 
bles he  has  discovered  after  death  in  the  vessels  of  the  brain  and 
cord.  But  he  states  that  Avhen  the  pressure  does  not  exceed  five 
atmospheres,  three  minutes  allowed  for  the  restoration  of  the  nor- 
mal pressure  will  be  found  to  prevent  the  formation  of  these 
globules  of  nitrogen.  Now,  we  find  the  Caisson  Disease  occurring 
when  the  pressure  does  not  exceed  two  atmospheres,  and  when  six 
to  eight  minutes  are  allowed  for  locking  out.  It  Avould  seem  that 
under  these  conditions,  the  gas  should  escape  through  the  lungs  as 


*  Comptes  Rendu s,  August,  1872,  and  February  and  March,  18T3. 


34 


rapidly  as  it  is  disengaged  from  the  blood.  Moreover,  we  find  that 
in  the  Caisson  Disease  the  attack  often  comes  on  several  minutes  or 
even  hours  after  leaving  the  compressed  air.  During  this  interval,  if 
any  free  nitrogen  were  circulating  with  the  blood,  it  should  constant- 
ly become  less  by  diffusion  through  the  pulmonary  membrane,  and  it 
is  scarcely  conceivable  that  if  the  quantity  at  the  moment  of  emerg- 
ing into  the  open  air  were  not  enough  to  produce  obstruction  of  the 
circulation,  such  an  effect  could  take  place  at  a  later  period. 

It  is  also  very  difficult  to  reconcile  with  M.  Bert's  theorj  the  fact 
of  the  comparative  immunity  from  danger  which  results  from  re- 
peated exposures  to  the  effects  of  compressed  air.  If  the  action  be 
that  of  purely  physical  causes,  habit  could  make  no  difference.  The 
obstruction  of  the  vessels  described  by  Bert  is  a  condition  of  which 
the  system  could  never  become  tolerant  by  frequency  of  repetition. 
On  the  other  hand,  it  is  perfectly  conceivable  that  vessels  which  are 
required  to  receive  a  varying  quantity  of  blood  at  different  times 
may  acquire  the  power  of  more  ready  adaptation  to  these  changes  of 
quantity,  since  this  is  only  an  extension  of  the  physiological  prin- 
ciple which  we  see  exemplified  in  all  organs  which  have  an  intermit- 
tent function.  Hence  this  objection,  which  lies  against  the  explana- 
tion of  M.  Bert,  does  not  api^ly  to  the  views  as  to  the  pathology  of 
the  disease  which  I  have  advanced. 

Thus,  while  recognizing  the  value  of  M.  Bert's  observations,  I  am 
still  of  the  opinion  that  he  is  in  error  in  applying  them  to  the  com- 
paratively low  pressures  and  gradual  decompression  which  are  con- 
sistent with  the  production  of  the  Caisson  Disease. 

In  order  further  to  test  this  question,  I  performed  the  following 
experiment :  The  pressure  in  the  caisson  being  about  35  lbs.  to  the 
square  inch,  a  dog  was  sent  down,  and  allowed  to  remain  seven  hours 
in  the  compressed  air.  At  the  end  of  that  time  I  went  down,  and 
after  killing  the  animal  with  prussic  acid,  I  opened  the  vessels  of  the 
neck,  and  allowed  four  ounces  of  blood  to  flow  into  a  six  ounce  vial. 
The  space  above  the  blood  was  then  completely  filled  with  olive  oil, 
and  a  cork,  pierced  by  one  leg  of  a  small  U-shaped  tube,  was  forced 
tightly  into  the  bottle,  displacing  a  portion  of  oil,  which  escaped 
through  the  tube.  By  this  arrangement  every  particle  of  air  was 
excluded  from  the  apparatus,  even  the  tube,  which  extended  a  little 
below  the  cork,  being  entirely  filled  with  oil.  The  object  of  the  oil 
was  to  avoid  the  difficulty  which  would  arise  from  coagulation  of  the 
blood  in  the  tube  if  blood  only  were  employed. 

The  apparatus  thus  arranged  was  then  taken  into  the  open  air. 
While  passing  through  the  lock  five  minims  of  oil  escaped  from  the 
tube,  which  amount  was  increased  during  the  next  half  iiour  to  eight 
minims.    The  temperature  of  the  caisson  and  that  of  the  external 


35 


air  were  almost  exactly  alike,  so  that  the  result  obtained  could  not  be 
influenced  by  contraction  or  expansion  due  to  temperature.  The 
eight  minims,  therefore,  represented  the  bulk  of  air  which  was  disen- 
gaged from  the  blood  in  consequence  of  the  removal  of  the  excess  of 
pressure.  This  is  only  of  the  bulk  of  the  blood  experimented 
upon.  Now  the  experiments  of  Demarquay*  show  that  from  80  to 
150  c.  centimetres  of  oxygen  can  be  thrown  into  the  veins  of  a  me- 
dium-sized dog  in  the  space  of  four  or  five  minutes,  without  pro- 
ducing serious  consequences  ;  and  other  observers  have  demonstrated 
that  air  slowly  introduced  into  the  veins  escapes  through  the  lungs, 
and  that  a  large  quantity  can  be  injected  in  this  way  without  danger. 

Hence  with  the  small  amount  of  air  which  my  experiment  shows 
to  be  disengaged  from  the  blood,  and  with  the  process  extended  over 
eight  or  ten  minutes  at  least,  it  seems  clear  that  we  cannot  explain  in 
this  way  the  phenomena  observed  in  the  Caisson  Disease. 

Causes. — The  one  essential  cause,  without  which  the  disease  can 
never  be  developed,  is  the  transition  to  the  normal  atmospheric  pres- 
sure, after  a  prolonged  sojourn  in  a  highly  condensed  atmosphere.  Hence 
we  have  to  consider  two  elements,  pressure  and  time.  As  the  mo- 
mentum of  a  moving  body  is  found  by  multiplying  the  weight  by  the 
velocity,  so  the  danger  in  these  cases  is  as  the  degree  of  pressure  to 
which  the  person  has  been  exposed,  multiplied  by  the  duration  of  the 
exposure. 

But  inasmuch  as  a  prolonged  sojourn  in  the  caisson  does  not  in 
every  case  produce  the  disease  (many  of  the  men  employed  escaping 
it  entirely),  \%  follows  that  there  must  be  concurrent  causes  which  de- 
termine its  development.  This  is  what  we  observe  in  many  other 
diseases  of  a  specific  origin.  Thus  the  essential  cause  of  intermit- 
tent fever  is  exposure  to  a  peculiar  malaria,  yet  only  a  portion  of 
those  so  exposed  are  affected  by  the  disease. 

The  first  of  the  concurrent  causes  of  the  Caisson  Disease  is  a 
special  predisposition.  This  is  occasionally  strongly  marked,  some 
persons  being  affected  by  a  short  exposure  to  a  low  pressure  from 
which  there  would  generally  be  experienced  no  inconvenience  what- 
ever. 

Tlie  study  of  these  cases  has  led  me  to  the  suspicion  that  they 
afford  a  key  to  the  singular,  though  very  common,  predisposition  to 
pams  in  the  limbs  on  the  approach  of  a  storm.  .  These  pains  are  gen- 
erally considered  to  be  of  a  rheumatic  character,  and  to  depend  upon 
the  dampness  of  the  atmosphere.  But  inasmuch  as  the  disease  we 
are  considering  affords  examples  of  pains  precisely  the  same  in  char- 
acter, but  immensely  intensified  in  degree,  resulting  from  the  diminu- 
tion of  an  atmospheric  pressure  to  which  the  system  had  adapted  it- 
*  Pneumatologie  MecUcale.  P.  664. 


36 


self,  and  irrespective  of  any  question  of  humidity,  analogy  suggests 
that  the  so-called  rheumatic  cases  are  simply  exaggerations  of  a  pre- 
disposition, identical  in  kind  with  the  one  under  discussion,  and  are 
produced  by  the  low  barometric  condition  of  the  atmosphere  which 
precedes  a  storm,  and  not  by  the  influence  of  moisture.  It  is  true 
that  the  change  in  the  pressure  is  insignificant  when  compared  with 
that  which  produces  the  Caisson  Disease,  but  it  is  supplemented  by  the 
immensely  greater  dm-ation  of  the  higher  pressure  to  which  the  sub- 
ject has  been  previously  exposed.  Persons  suffering  in  the  manner 
referred  to,  regard  themselves  as  walking  hygrometers,  and  are  ac- 
customed to  say,  ' '  I  feel  the  dampness  in  my  bones. "  I  would  sug- 
gest that  they  are  rather  barometers,  perhaps  quite  as  sensitive  as 
the  instrument  of  Torricelli. 

Perhaps  the  most  frequent  exciting  cause  of  the  Caisson  Disease  is 
too  rapid  locking  out.  Indeed,  it  is  altogether  probable  that  if  suffi- 
cient time  w^ere  allowed  for  passing  through  the  lock,  the  disease 
would  never  occur.  But  w^hat  is  sufl[icient  time  for  one  is  too  short  a 
time  for  another,  and  as  no  work  could  be  accomplished  if  the  time 
in  the  lock  were  indefinitely  prolonged,  all  that  can  be  done  is  to  fix 
upon  a  duration  for  the  process  of  locking  out  which  shall  be  propor- 
tioned to  the  pressure,  and  as  great  as  is  consistent  with  the  circum- 
stances, and  then  to  see  that  the  rule  is  rigidly  observed.  The  natu- 
ral impatience  of  the  men  to  reach  their  homes,  makes  the  dela}^  in 
the  lock  irksome,  and  great  firmness  is  required  on  the  part  of  the 
lock-tender  to  prevent  the  escape-cocks  being  opened  more  widely 
than  is  consistent  with  safety.  In  locking  out,  at  least  five  minutes 
should  always  be  allowed  for  each  additional  atmosphere  of  pressure. 

Neimess  to  the  Work. — Unquestionably  the  liability  to  the  Caisson 
Disease  is  greatest  in  those  exposed  for  the  first  time  to  the  influence 
of  the  compressed  air.  New  hands  are  very  apt  indeed  to  suffer  more 
or  less  during  the  first  week,  and  a  number  of  the  severest  cases  that 
came  to  my  nptice,  occurred  in  men  who  had  worked  but  a  single 
watch,  though  first  attacks  were  much  more  likely  to  occur  after  the 
second  watch  of  the  first  day.  Those  least  affected  were  such  as 
began  work  when  the  pressure  was  comparatively  slight,  and  contin- 
ued without  intermission  as  the  pressure  increased.  It  seemed  that 
the  system  after  a  time  became  adapted  to  the  changed  conditions, 
and  was  protected,  in  a  measure,  from  their  effects.  Nevertheless, 
some  serious  cases  occurred  among  the  old  hands,  especially  when  for 
any  reason  their  stay  in  the  caisson  was  prolonged  beyond  the  usual 
time,  thus  showing  that  their  immunity  was  merely  relative.  A 
sudden  increase  of  pressure,  also,  even  though  very  slight,  was  cer- 
tain to  develop  new  cases— men  thoroughly  inured  to  the  work 
often  being  affected  under  such  ckcumstances. 


37 


Fullness  of  Habit. — After  the  work  in  the  Xew  York  caisson  had 
been  some  months  in  progi'ess  it  was  observed  that  there  w^as  a  pre- 
ponderance of  stout,  heavily-built  men  among  those  taken  sick. 
This  led  me  to  examine  my  records  carefully  in  reference  to  this 
point.  I  found  that  up  to  May  22,  the}^  embraced  86  cases  of  well- 
marked  Caisson  Disease.  These  I  di\ided  into  three  classes,  accord- 
ing to  the  build  of  the  individual.  Those  who  were  tall  in  propor- 
tion to  then-  weight,  and  rather  lean  in  flesh,  were  classed  as  spare  ; 
those  who  were  thick-set  and  muscular,  without  being  fat,  were  set 
down  as  medium  ;  and  those  with  prominent  abdomen,  full  cheeks, 
and  general  tendency  to  obesity,  were  stj'led  Jieavy.  The  86  cases  of 
illness  were  found  to  be  distributed  among  these  three  classes  as  fol- 
lows :  Spare,  28  ;  medium,  22  ;  heavy,  36. 

Considering  that  among  laborers  below  the  age  of  45  (and  none  of 
the  cases  were  above  that  age),  the  class  described  as  heavy  are  very 
much  in  the  minority,  these  figures  were  suificiently  striking. 

In  order  to  arrive  at  the  converse  of  this  I  desired  the  time-clerk 
to  prepare  a  list  of  those  who  had  lost  least  time  from  illness,  i.e., 
those  least  affected  by  the  work.  The  figures  in  this  case  were  even 
more  striking.  The  list  comprised  the  names  of  42  men,  who  were 
classified  as  follows  :  Spare,  25 ;  medium,  14  ;  heavy,  3. 

I  next  separated  the  severer  cases  of  illness,  which  were  marked 
by  parah^sis ;  of  these  there  were  13 :  Spare,  2  ;  medium,  3  ;  heavy, 
8.  Those  who  had  died  up  that  time,  three  in  number,  were  alllieavy 
men. 

These  results  may  be  tabulated  as  follows : 


Spare. 

Medium. 

Heavy. 

Total. 

Lost  little  or  no  time  from  sickness. . . 

25 

14 

3 

42 

28 

22 

36 

86 

Paralyzed  

2 

3 

8 

13 

Died  

8 

3 

These  figm-es  show  unmistakably  that  a  tendency  to  fullness  of 
habit  renders  work  in  a  compressed  atmosphere  much  more  hazard- 
ous. Persons  of  this  build  have  more  fluids  in  the  body,  the  distribu- 
tion of  which  is  changed  by  the  pressure,  in  the  manner  before 
stated,  and  it  is  therefore  not  suiprisiug  that  the  effect  upon  them 
should  be  greater  than  upon  lean  and  siuewj-  persons,  whose  bodies 
contain  a  minimum  of  fluid. 

Severe  Exertion  Immediately  after  Leaving  the  Caisson. — As  at  the 
moment  of  going  out  of  the  compressed  air  the  system  undergoes  a 


38 


violent  reaction,  it  is  manifestly  unfitted  to  bear  in  addition  a  severe 
tax  upon  the  muscular  strength.  Hence,  the  ascent  of  a  long  flight 
of  stairs,  immediately  after  leaving  the  air-lock,  is  as  wrong  in  theory 
as  it  has  proved  bad  in  practice  Dr.  Jaminet  has  described  most 
graphically  the  ill  eifects  arising  from  this  cause  at  St.  Louis,  and 
the  relief  experienced  when  the  men  were  saved  the  necessity  of 
climbing  the  steps  by  the  substitution  of  a  steam  elevator.*  Con- 
trast this  with  the  experience  of  M.  Triger,  whose  apparatus  at  Cha- 
hmnes  was  so  arranged  that  the  ascent  of  the  ladder  took  place  in 
the  compressed  ah-,  the  lock  being  placed  at  the  top  instead  of  the 
bottom  of  the  shaft.  He  found  that  the  men  ascended  a  distance  of 
70  feet  without  becoming  in  the  least  out  of  breath ;  making  the 
ascent,  in  fact,  much  more  easily  than  if  it  had  been  in  the  open  air. 

I  hoped  at  one  time  that  an  opportunity  would  be  afforded  at  the 
New  York  caisson  for  obtaining  some  data  bearing  upon  this  point. 
During  the  early  part  of  May  an  elevator  was  arranged,  but  unfortu- 
nately just  at  that  period  great  changes  took  place  in  the  force,  and 
at  the  same  time  various  interruptions  in  the  work  occurred,  so  that 
the  matter  was  hopelessly  complicated,  and  no  data  for  comparison 
could  be  obtained. 

Tlie  Abuse  of  Alcohol. — Sev^aral  writers  have  remarked  that  habit- 
ual drinkers  are  more  likely  to  be  affected  by  compressed  air  than 
those  who  used  spirits  moderately  or  not  at  all.  It  is  stated  by  the 
director  of  the  work  at  Douchyf  that  the  attacks  from  which  the 
men  suffered  were  "  almost  always  coincident  with  some  excess  com- 
mitted in  the  interval  of  the  shifts."  It  is  easy  to  perceive  that  as 
the  disease  is  characterized  by  cerebral  congestion,  the  abuse  of  alco- 
hol, which  has  a  tendency  to  produce  the  same  result,  would  act  as  a 
predisposing  cause.  Although  no  cases  directly  attributable  to  this 
cause  came  under  my  observation,  I  have  no  doubt  that  there  is 
danger  from  it;  and  I  therefore  rejected  several  men  who  applied  for 
work  in  the  caisson,  for  no  other  reason  than  that  their  appearance 
indicated  an  habitual  excessive  use  of  alcohol. 

Entering  the  Caisson  Fasting.  — Dr.  Jaminet  insists  very  strongly 
upon  the  influence  of  this  cause,  and  cites  instances  to  prove  his 
position.  Several  cases  corroborative  of  his  views  occurred  under 
my  observation.  One  of  the  rules  for  the  men  working  in  the  New 
York  caisson,  prohibited  entering  the  compressed  air  without  having 
taken  food,  and  in  addition  to  this  each  new  hand  was  especially 
cautioned  as  to  the  danger  of  disregarding  this  precaution,  and  the 
foremen  were  directed  to  use  every  effort  to  secure  its  observance. 
Yet  notwithstanding  all  this  a  number  of  very  severe  attacks  were 

*See  Dr.  J.'s  Report,  p.  120. 

t  Annales  d'Hyg.  Pub.  et  de  Med.   Legale,  1854. 


39 


foimd  to  b3  coincident  witli,  if  not  dependent  upon,  violations  of  this 
rule.  In  these  cases  epigastric  pain  and  retching  were  prominent 
symptoms.    (See  Case  XXI.,  p.  47.) 

Treatment. — The  treatment  of  this  disease  will  depend  upon  the 
severity  of  the  case,  and  the  presence  or  absence  of  gastric  symp- 
toms or  of  paralysis  If  we  have  to  deal  with  the  neuralgic  pains 
only,  the  chief  reliance  must  be  upon  anodynes,  administered  with  a 
liberal  hand.  Fortunately  the  pain,  though  very  severe  while  it 
lasts,  is  in  most  cases  of  short  duration,  the  attack  passing  off 
usually  in  a  few  hours. 

It  is,  therefore,  quite  practicable  to  keep  the  patient  under  the 
influence  of  morphine  during  the  whole  time,  and  thus  enable  him  to 
escape  entirely  all  extreme  suffering.  But  large  doses  will  be 
required,  the  intense  pain  inducing  a  remarkable  tolerance  of  the 
drug.  It  was  my  habit  to  give  half  a  grain  of  morphine  at  the 
outset,  and  a  quarter  of  a  grain  every  half  hour  afterward  until 
relief  was  obtained.  When  emplo^'ed  hypodermically,  which  is  the 
method  affording  most  prompt  relief,  somewhat  smaller  do^cs  may 
be  used. 

In  some  instances  I  have  obtained  the  very  best  results  from  hypo- 
dermic injections  of  atropine  at  the  seat  of  pain ;  but  in  other  cases 
it  failed  to  procure  relief,  and,  upon  the  whole,  I  consider  it  inferior 
to  morphine. 

Dr.  Jaminet,  regarding  the  affection  as  wholly  the  result  of 
exhaustion,  relies  entirely  upon  stimulants  and  concentrated  nourish- 
ment, ignoring  the  aid  of  anodjnies  altogether.  I  can  see  no  reason 
for  this,  even  admitting  to  the  fullest  extent  his  theory  of  the  dis- 
ease, for  nothing  can  be  more  exhausting  than  the  intolerable  pain 
which  characterizes  this  affection,  and  nothing  could  act  more 
promptly  as  a  restorative  than  an  efficient  anodyne. 

Starting  from  the  theory  already  given  as  to  the  mode  in  which 
the  disease  is  produced  (a  theory  which  was  constructed  wholly  upon 
the  observations  of  others),  I  was  led  to  the  idea  that  benefit  would 
be  derived  from  the  use  of  an  agent  that  would  induce  contraction  of 
the  capillaries,  and  thus  correct  the  want  of  tone  which  I  considered 
to  lie  at  the  foundation  of  the  difficult3\  For  this  purpose  I  pro- 
posed the  use  of  ergot  before  I  had  ever  seen  a  case  of  the  dis- 
ease. I  reasoned  that  it  would  be  useful,  first,  by  contracting  the  ves- 
sels of  the  brain  and  spinal  cord,  and  relieving  their  congested  state  : 
and  secondly,  by  restoring  tone  to  the  superficial  vessels,  and  thus 
imparting  vigor  to  the  circulation. 

An  extended  trial  warrants  me  in  sajing  that  the  results  have  jus- 
tified the  theory.  In  my  hands,  though  not  always  successful,  ergot 
has  certainly  been  very  useful  in  a  considerable  number  of  cases. 


40 


I  have  seen  very  severe  pain  completely  relieved  within  half  an  hour 
after  the  administration  of  a  di*achm  of  the  fluid  extract.  In  other 
instances,  unsteadiness  of  the  limbs,  which  seemed  about  to  usher  in 
paralysis,  has  yielded  promptly  to  one  or  two  doses. 

But  perhaps  the  best  evidence  of  its  usefulness  is  to  be  found  in 
the  preference  for  it  of  the  night-porter,  who  had  charge  of  the  hos- 
pital at  night,  and  who  was  instructed  in  the  use  of  the  few  medi- 
cines employed,  and  treated  such  cases  as  occurred  among  the  men 
composing  the  night  gangs.  Having  both  morphine  and  ergot  at 
hand,  he  gradually,  and  of  his  own  accord,  almost  abandoned  the 
former,  declaring  that  the  ergot  was  more  prompt  and  certain  in 
relieving  the  pains.  This  from  an  intelligent,  unprejudiced,  non- 
professional source,  is  strong  testimony  in  favor  of  the  eflSciency  of 
the  drug. 

I  was  in  the  habit  of  giving  a  teaspoonful  of  Squibbs'  fluid  extract, 
and  repeating  the  dose  in  half  or  three-quarters  of  an  hour,  unless 
the  pain  was  relieved.  In  one  case  ergotine  was  injected  hypoder- 
mically  ;  but  so  much  irritation  was  caused  at  the  point  of  insertion 
that  the  experiment  was  not  repeated. 

Frictions,  with  or  without  stimulating  liniments,  are  very  generall}' 
resorted  to,  and  seem  sometimes  to  give  momentary  relief,  but  it  ap- 
pears to  me  to  be  rather  by  occupying  the  attention  of  the  patient 
than  by  any  action  occasioned  in  the  part. 

In  one  of  my  cases  of  pain  in  the  knee,  compression  of  the  femo- 
ral artery  with  the  fingers  w^as  tried.  The  pain  was  considerably  re- 
lieved for  a  few  minutes,  but  soon  acquired  its  former  severity.  In 
another  case  a  tourniquet  was  applied  so  as  to  interrupt  the  venous 
as  well  as  the  arterial  circulation,  but  with  no  better  result. 

In  some  instances  where  the  pain  was  confined  to  a  particular  lo- 
cality, I  had  the  part  immersed  in  hot  water,  with  the  effect  of  caus- 
ing temporary  relief.  But  the  use  of  the  general  hot  bath  was  not 
advised,  as  I  considered  it  unsafe  to  increase  the  already  existing  re- 
laxation of  the  vessels.  In  several  of  Dr.  Jaminet's  cases  paralysis 
came  on  while  in  the  hot  bath,  and  he  therefore  interdicted  its  use. 

Toward  the  last  of  my  experience  I  applied  cold  to  the  spine  in 
two  cases,  with  apparent  benefit  in  each.  In  one  of  these  cases,  in 
which  there  was  paralysis  of  the  bladder,  the  improvement  after  a 
cold  douche  to  the  spine  was  marked. 

In  one  case  of  paraplegia,  dry  cups  applied  to  the  spine  in  the  lum- 
bar region  were  unmistakably  beneficial. 

Electricity  was  tried  by  Dr.  Jaminet  at  St.  Louis,  but  was  found 
to  be  useless. 

Epigastric  pain  is  almost  always  relieved  at  once  by  the  use  of  an 
alcoholic  stimulant  with  ginger,  as  employed  by  Dr.  Jaminet. 


41 


Vomiting  is  best  treated  with  sinapisms  to  the  epigastrium,  and 
swallowing  small  bits  of  ice.  A  full  dose  of  calomel  was  effectual 
in  one  of  my  cases  which  resisted  all  other  treatment. 

When  paralysis  occurs,  it  is  to  be  treated  on  general  principles. 
Cups  or  leeches,  with  douches  and  frictions  to  the  spine,  may  be  use- 
ful ;  and  if  the  case  be  protracted,  the  use  of  strjxhnine  may  be  called 
for.  The  bladder  will  almost  certainly  be  involved,  requiring  the 
constant  employment  of  the  catheter. 

The  cerebral  symptoms  which  occasionally  occur,  are,  Avith  the  ex- 
ception of  coma,  so  transient  in  their  natm*e  as  to  call  for  no  special 
treatment.  Coma,  when  it  takes  place,  is  to  be  managed  according  to 
the  circumstances  of  the  case,  as  when  proceeding  from  other  causes. 
If  accompanied  by  a  full,  strong  puLse,  venesection  may  be  expe- 
dient. 

There  remains  to  be  considered  a  plan  of  treatment  originally  sug- 
gested by  Pol,  and  carried  out  to  some  extent  by  Foley,  viz. ,  return- 
ing the  patient  at  once  into  the  compressed  air. 

It  frequentl}'  happened  under  ni}^  observation,  that  pains  not  suffi- 
ciently severe  to  deter  the  men  from  retm^ning  to  work,  were  promptly 
dissipated  on  entering  the  caisson,  to  retm-n  again  on  coming  into  the 
open  air.  Indeed,  I  do  not  remember  a  single  exception  to  the  rule, 
that  any  pain  which  may  have  been  felt  before,  disappeared  almost 
imme<:liately  on  going  below. 

Foley  says,  as  the  result  of  his  experience  :  "A  true  specific  is  re- 
tm*ning  to  the  caisson,  thi'ough  which  means  all  such  accidents  (pains, 
vertigo,  etc^f)  speedily  disappear.  It  is  to  be  resorted  to  unhesitat- 
ingly in  all  thi-eatening  cases,  and  the  pressure  should  be  admitted 
rapidly." 

But  the  means  of  access  to  the  caisson  are  usually  such  that  it 
would  be  difficult  to  remove  a  patient  into  it,  even  if  he  could  be 
comfortably  cared  for  while  there,  or  if  his  presence  would  not  in- 
terfere with  the  work.  It  would,  therefore,  be  desu*able  to  have 
facilities  for  employing  compressed  air  at  some  point  above  ground 
which  would  be  easily  accessible. 

My  plan  would  be  as  follows  :  Let  them  be  constructed  of  iron  of 
sufficient  thickness,  a  tube  9  feet  long  and  3^  feet  in  diameter,  having 
one  end  permanently  closed,  and  the  other  provided  with  a  door  open- 
ing inward,  and  closing  air-tight.  This  tube  to  be  placed  horizon- 
tally, and  provided  with  ways  upon  which  a  bed  could  be  slid  into  it. 
Ver}'  strong  plates  of  glass  set  in  the  door  and  in  the  opposite  end 
would  admit  the  light  of  candles  or  gas  jets  placed  immediately  out- 
side. This  apparatus  should  be  connected  by  means  of  a  suitable  tube 
with  the  pipe  which  conveys  the  air  from  the  condensers  to  the 
caisson?  An  escape-cock  properl^^  regulated  would  allow  the  constant 


42 


escape  of  sufficient  air  to  preserve  the  necessary  purity  of  the  at- 
mosphere within. 

The  bed  containing  the  patient  having  been  slid  into  the  chamber, 
the  door  is  to  be  closed,  and  the  pressure  admitted  gradually  until  it 
nearly  or  quite  equals  that  in  the  caisson.  This  should  be  continued 
until  the  patient  indicates  by  a  signal  previously  concerted,  that  the 
pain  is  relieved.  The  pressure  should  then  be  reduced  by  degrees, 
carefully  adjusted  to  the  effect  produced,  until  at  last  the  normal 
standard  is  reached.  By  occupying  several  hours,  if  necessary,  in  the 
reduction  of  the  pressm*e,  it  is  probable  that  a  return  of  the  pain 
could  be  avoided. 

The  apparatus  once  provided,  there  would  be  no  difficulty  in  car- 
rying out  the  plan  in  any  case  of  such  severity  as  to  resist  other 
treatment.  I  should  expect  the  very  best  results  from  it  in  cases  of 
extreme  pain,  or  in  the  very  outset  of  paralysis  not  dependent  upon 
extravasation  of  blood. 

Of  course  the  secondary  conditions  which  arise  in  protracted  cases 
would  not  be  capable  of  direct  relief  by  simply  reproducing  the  phys- 
ical conditions  existing  in  the  caisson.  The  most  that  might  be 
hoped  for  in  such  cases  would  be  that  the  pressure  might  result  in 
giving  a  new  impulse  to  the  circulation  in  the  congested  part,  and 
thus  favor  resolution. 

Reasoning  from  his  view  of  the  pathology  of  the  disease,  M.  Bert 
has  proposed  the  inhalation  of  oxygen,  in  order  to  displace  the  free 
nitrogen  from  the  blood  by  diffusion.  Experiments  upon  animals 
demonstrated  that  the  sounds  produced  in  the  heart  by  the  presence 
of  free  nitrogen,  speedily  disappeared  when  the  animal  was  made  to 
inhale  oxygen,  the  nitrogen  diffusing  into  this  gas  much  more  readily 
than  into  common  air.  But  though  immediate  death  was  averted  by 
this  expedient,  paralysis  nevertheless  occurred,  and  post  mortem 
examination  showed  the  presence  of  bubbles  of  nitrogen  in  the 
vessels  of  the  cord. 

A  tendency  to  pulmonary  congestion  seems  to  be  induced  by  high 
atmospheric  pressure  in  certain  rare  instances.  Such  cases  are  men- 
tioned by  Frangois  and  Jaminet,  and  two  instances  came  under  my  own 
observation,  one  of  which  was  almost  instantly  fatal.    (Case  XXX.) 

The  mechanism  by  which  these  congestions  are  produced  is  not 
apparent.  If  in  every  instance  they  occurred  immediately  upon 
passing  from  the  caisson  into  the  open  air,  it  might  be  inferred  that 
the  expansion  of  the  air  contained  within  the  lung  produced,  in  some 
way,  an  interference  vnth  the  pulmonary  circulation.  But  inas- 
much as  a  rapidly  fatal  congestion  may  come  on  an  hour  or  more 
after  leaving  the  caisson,  this  explanation  is  not  sufficient.  The 


43 


subject  is  involved  in  obscurity,  which  can  be  removed  only  by  the 
study  of  a  larger  number  of  cases  than  have  occurred  as  yet. 


CHAPTER  SIXTH. 

ILLUSTRATIVE  CASES. 

The  following  cases  have  been  selected  from  my  notes  as  illustrat- 
ing the  various  affections  resulting  fi-om  compressed  air  which  have 
been  described  in  the  foregoing  text.  Also,  a  few  cases,  as  will  be 
seen,  have  been  borrowed  from  other  sources. 

Case  I. — John  Campbell,  lock-tender,  on  the  11th  of  February,  was 
"caught  in  the  lock, "  ^.  e.,  found  himself  unable  to  equalize  the 
pressure  in  the  left  ear.  The  pain,  however,  not  being  severe,  he 
completed  his  day's  w^ork.  The  following  night  was  taken  with 
very  severe  pain  in  the  ear,  which  continued  without  intermission 
until  the  20th,  when  a  profuse  discharge  of  pus  fi-om  the  external 
ear  set  in,  affording  relief  from  the  pain.  Under  the  use  of  carbolic 
acid  injections  the  discharge  soon  ceased,  leaving  the  hearing  unim- 
paired. 

Case  11. — John  Hicks.  Taken  on  the  17th  of  May,  while  in  the 
lock  going  down,  with  severe  pain  in  the  right  ear,  followed  by  a 
slight  discharge  from  the  external  meatus.  No  sensation  as  of  any- 
thing giving  way  in  the  ear.  He  completed  his  watch  and  then 
reported  to  me.  On  examination,  the  drum  of  the  eai'  was  found  to 
be  rupturec?  at  its  upper  edge.  The  opening  was  nea^'ly  circular,  and 
rather  less  than  a  line  in  diameter.  The  patient  preferred  to  give  up 
his  place  at  once,  and  did  not  report  again.  Though  he  stated  that 
he  had  had  no  previous  trouble  with  the  ear,  the  fact  of  the  discharge 
when  the  membrane  was  ruptured,  leads  to  the  suspicion  that  there 
was  catarrh  of  the  middle  ear,  which  probably  accounted  also  for  the 
stoppage  of  the  Eustachian  tube. 

Case  III. — (Francois).*  Patient  at  Argenteuil  seized  with  otalgia 
on  coming  out  of  the  caisson,  where  the  pressure  was  13  lbs.  to  the 
inch.  Pain  persisted  for  15  days  without  intermission,  notwithstand- 
ing the  most  active  treatment,  including  pm-gatives  and  the  applica- 
tion of  leeches  and  antimony  behind  the  ear.  Condition  of  the 
tube  or  of  the  di*um  not  stated. 

Case  IV. — Patrick  O'Farrell.  Reports  March  11th,  that  he  was 
taken  four  days  ago,  on  going  down  into  the  caisson,  with  pain  in 
the  region  of  the  fi-ontal  sinus.  On  coming  up,  the  pain  was  in- 
creased, and  there  was  bleeding  from  the  nose.  The  pain  has  con- 
tinued ever  since.    Ordered  anodynes  and  hot  fomentations. 


*  Annales  cl'Hygiene  Publique,  et  de  Med.  Leg.  T.  XIV.  i860. 


44 


14th.    Reports  for  duty. 

Case  V. — Hugh  Rourke.  March  12th,  while  gomg  home  in  the 
evening,  was  taken  with  severe  pain  in  the  right  knee.  Pain  continued 
all  night.  On  the  following  morning  he  returned  to  his  work,  when, 
on  entering  the  caisson,  he  found  that  the  pain  ceased  at  once.  On 
coming  up  again  it  returned  with  increased  severity.  Controlled  by 
morphine. 

Case  VL — John  Roland.  Taken  on  March  8ch,  while  in  a  car 
going  home.  Dizziness  and  loss  of  strength ;  feet  cold,  head  hot ; 
unable  to  stand,  but  still  not  paralyzed — simply  weak.  No  pain. 
Profuse  cold  perspu-ation.  Recovered  perfeetl}"  in  a  few  hours  with- 
out treatment. 

Case  VII. — Alfred  Symes.  Suffered  somewhat  with  pain  in  the 
right  knee,  on  coming  up  from  the  caisson  on  the  10th  of  May.  On 
the  11th  he  worked  as  iisual,  experiencing  no  pain.  On  the  12th 
(Sunday),  not  having  been  in  the  caisson  since  the  day  previous,  he 
was  taken  with  severe  pain  in  the  same  knee.  When  he  reported  to 
me,  on  the  14th,  he  was  suffering  with  a  swelling  of  the  knee,  ac- 
companied by  heat  and  extreme  tenderness,  especially  just  above  the 
patella.  He  was  ordered  to  apply  fomentations,  with  a  hot  solution 
of  bicarbonate  of  potash.  Under  this  treatment  the  pain  and  swell- 
ing soon  subsided.  On  the  15th,  there  was  a  greenish  yellow  tinge 
of  ecch3^mosis  over  the  front  of  the  knee,  for  a  space  as  large  as  the 
palm  of  the  hand. 

Case  YHI.— Samuel  Mitchell.  Worked  for  one  watch  only  on  the 
14th  of  May,  being  his  first  experience  in  compressed  au\  After  the 
first  watch,  on  the  15th,  he  was  taken  with  pain  in  both  the  upper 
and  lower  extremities,  and  also  in  the  chest  and  bowels.  This  was 
followed  by  giddiness  and  vomiting.  There  was  paralysis  of  the  left 
leg  and  weal^Jiess  of  the  right  arm.  Profuse  sweating.  Pulse  80. 
Ergot  and  chloral  given.  Paral3'sis  passed  off  in  two  hours,  leaving 
slight  pain  in  the  ai'ms  and  wrists.  The  bowels  had  not  been  opened 
for  several  days. 

Case  IX.— John  Kennedy.  This  patient  had  engorgement  of  the 
left  mammary  gland,  recurring  each  day  after  coming  out  of  the 
caisson,  and  especially  after  the  second  watch.  There  was  marked 
swelling  and  tenderness,  which  disappeared  during  the  afternoon  and 
evening,  to  recui-  again  on  the  following  day.  This  continued  for 
more  than  a  week. 

Case  X. — Joseph  Hatch.  Taken  sick  on  the  17th  of  May,  after 
his  first  watch.  Epigastric  pain  and  pain  in  the  legs  and  arms,  fol- 
lowed by  paraplegia.  Treated  with  ergot  only.  At  the  end  of  four 
hours  he  had  recovered  the  use  of  his  limbs,  and  the  pain  had  ceased, 
but  there  remained  a  giddiness  which  prevented  his  standing.  By 


45 


the  following  clay  lie  was  able  to  walk  about,  but  the  giddiness  had 
not  entirely  disappeared  when  I  last  saw  him,  May  21st. 

Case  XI. — E.  Riley.  Taken  sick  Feb.  16th,  one  hour  after  leaving 
the  caisson.  Pressure  26  lbs.  Epigastric  pain  and  pain  in  the  legs. 
No  loss  of  sensibility.  Profuse  cold  perspiration.  Pulse,  when  I  saw^ 
him,  two  hours  after  the  commencement  of  the  attack,  was  96.  The 
pain,  which  at  first  w^as  veiy  severe,  had  hy  this  time  become  much  less. 
Gave  him  an  ounce  of  brandy  and  a  teaspoonf  ul  of  fluid  extract  of 
ergot.  In  10  minutes  the  pulse  had  fallen  to  82.  Was  able  to  resume 
work  next  day. 

Case  XII. — Joseph  Brown,  foreman,  American,  aged  about  28. 
Taken  on  the  28th  of  February,  about  an  hour  after  coming  up  from 
a  three  hours'  w'atch.  Excessive  pain  in  left  shoulder  and  arm,  com- 
ing on  suddenly,  "like  the  thrust  of  a  knife."  Pain  continued  uatil 
he  went  down  again  for  the  afternoon  watch,  when  it  ceased  imme- 
diately. On  the  following  morning  there  was  a  spot  on  the  shoulder 
and  one  on  the  arm,  at  the  points  where  the  pain  had  been  most 
severe,  where  the  skin  was  speckled  with  minute  bright  red  points  of 
extravasated  blood.  Had  had  no  pain  since  the  day  before,  but  the 
parts  were  tender  to  the  touch,  with  at  the  same  time  a  feeling  of 
numbness. 

Case  XIII. — Henry  Stroud,  a  diver  by  occupation,  began  work  on 
the  morning  of  April  2d.  Half  an  hour  after  coming  up  from  the 
first  watch,  was  taken  with  numbness  and  loss  of  power  in  the 
right  side,  also  dizziness  and  vomiting.  This  was  followed  by  severe 
pain  over  t^e  whole  body.  Excessive  perspiration.  Was  treated 
with  stimulants  and  ergot,  and  in  five  hours  was  well  enough  to  re- 
turn home. 

Case  XIV.— John  Barnabo,  Italy,  43,  reports  that  on  the  13th  of 
March,  while  in  a  car  returning  home,  he  was  taken  with  severe  pain 
in  both  arms.  This  was  followed  by  dimness  of  sight  and  partial 
unconsciousness.  Extremities  very  cold.  Remained  in  this  condi- 
tion for  tw^o  hours.  Was  obliged  to  keep  his  bed  for  three  days. 
For  a  week  afterward  was  unable  to  work,  feeling  very  much  op- 
pressed about  the  chest.  Had  no  medical  attendance.  Had  a  simi- 
lar but  less  severe  attack  about  a  month  previously. 

Case  XV. — J.  Avers.  Taken  on  the  7tli  of  April  with  very  severe 
pain  in  both  knees,  coming  on  within  a  few  minutes  after  leaving  the 
caisson.  A  drachm  of  the  extract  of  ergot  was  given  every  hour  for 
three  hours,  then  two  more  doses  at  intervals  of  two  hours,  after 
which  he  was  completely  relieved. 

Case  XVI. — Frank  Murphy.  Taken  sick  April  8th,  after  the  sec- 
ond watch  of  his  first  day  in  the  caisson.  Extremely  severe  pains  in 
both  knees  and  in  the  right  shoulder ;  -^^  of  a  grain  of  atropine  was 


46 


injected  beneath,  the  skin  of  the  shoulder,  but  aiforded  no  relief. 
Half  a  grain  of  morphia  by  the  mouth,  did  not  check  the  pain.  Legs 
placed  in  hot  water,  which  gave  immediate  relief.  Ergot  was  also 
given  in  drachm  doses  hourly.  Returned  home  much  better,  but  the 
pain  subsequently  returned,  and  was  very  severe  at  times  for  several 
days. 

Case  XVII. — Charles  Peterson.  Taken  on  the  11th  of  April  with 
severe  pain  in  both  legs  and  in  the  right  arm.  Was  relieved  by  ergot, 
but  had  severe  pain  each  day  afterward  on  coming  up.  On  the  15th 
he  was  ordered  a  teaspoonful  of  the  fluid  extract  of  ergot,  fom-  times 
a  day,  after  which  there  was  no  further  complaint. 

Case  XVIII. — Card,  foreman.  Taken  on  the  17th  of  April,  after 
the  first  watch,  with  quivering  in  the  thighs,  followed  by  loss  of 
power  in  the  lower  extremities,  and  anasthesia.  There  was 
also  partial  paralysis  of  the  bladder.  These  symptoms  con- 
tinued until  the  19th,  when  they  disappeared,  leaving  great  sore- 
ness of  the  muscles  of  the  calves.  After  the  paralysis  had  passed  off 
in  a  measure,  he  went  down  again  into  the  caisson  and  remained  for 
a  short  time  with  decided  benefit,  The  improvement  continued  after 
returning  to  the  open  air.  He  had  no  other  medication  than  two 
doses  of  ergot. 

Case  XIX. — James  HefCener.  Attacked  May  2d,  ^oon  after  leav- 
ing the  caisson,  with  pain  in  the  limbs  and  in  the  epigastrium,  fol- 
lowed by  vomiting  of  large  pieces  of  undigested  meat.  Eyes  swollen 
and  very  much  injected;  extreme  giddiness;  pulse  80,  and  small. 
Vomiting  continued  at  intervals  for  24  hours.  Bowels  had  not  been 
moved  for  48  hours. 

Was  treated  with  morphia  and  ergot,  but  the  vomiting  continuing, 
a  scruple  of  calomel  was  given  on  the  3d,  which  had  the  effect  of 
quieting  the  stomach,  and  at  the  same  time  of  relieving  the  bowels, 
after  which  the  patient  quickly  recovered. 

Case  XX. — Thos.  Kirby.  Taken  April  30,  with  severe  pain  in 
the  right  forearm.  The  patient  was  seen  by  Dr.  G  M.  Beard,  at 
whose  suggestion  I  injected  into  the  middle  of  the  palmar  aspect  of 
the  forearm  two  minims  of  a  solution  of  ergotine,  each  minim  con- 
taining a  grain  of  the  drug.  The  following  day,  considerable  swell- 
ing had  taken  place  at  the  point  of  puncture.  The  original  pain  still 
continued,  though  less  severe.  On  the  4th  day  of  May,  the  patient 
presented  himself  with  a  similar,  though  more  extensive,  swelling  on 
the  other  side  of  the  arm,  the  previous  swelling  having  disappeared. 
This  secondary  swelling  followed  very  closely  upon  the  first.  It  sub- 
sided promptly  under  the  use  of  cold  applications ;  but  on  the  10th, 
another  similar  swelling  appeared  on  the  part  of  the  arm  above  the 
elbow.    It  was  excessively  hot  and  painful.    By  the  continuous  use 


47 


of  ice,  it  was  soon  dissipated  witlioiit  suppuration.  The  patient  did 
not  enter  the  caisson  from  the  time  of  the  first  attack  until  his  final 
recovery. 

Case  XXI. — Brune  Wieland,  Germany,  aged  23.  Attacked  on  the 
8th  of  ]May,  after  working  two  hoiu's  in  the  caisson,  Avhich  he  entered 
for  the  first  time,  and  without  having  taken  food.  The  attack  began 
•with  pain  in  the  epigastrium,  and  vomiting  soon  followed  by  para- 
plegia, and  gi-eat  depression.  Respiration  40,  pulse  100,  and  very 
feeble.  Stimulants  brought  about  a  prompt  reaction.  The  power  of 
motion  was  soon  regained,  but  there  was  not  sufficient  strength  in  the 
legs  to  stand.  Paralysis  of  the  bladder.  On  the  following  day  he  was 
perfectly  comfortable,  though  still  too  Aveak  to  stand.  Bladder  still 
paralyzed.  Sent  to  the  hospital,  after  which  there  is  no  record  of  his 
case. 

Case  XXII. — Patrick  Rogers,  Ireland,  aged  40,  reported  at  my 
office  at  the  pier  that  the  day  previous  he  was  taken  while  on  the 
ferry-boat  going  home,  with  pain  in  the  right  side,  soon  followed  by 
loss  of  feeling  and  power  to  move  or  stand.  This  was  about  thi-ee- 
quarters  of  an  hour  after  leading  the  caisson,  where  the  pressure  was 
26  lbs.  to  the  inch.  On  the  arrival  of  the  boat  he  was  placed  in  a 
hack,  and  taken  honie.  According  to  his  account,  he  was  for  four 
hours  completeh'  paralyzed  in  the  legs,  and  partly  so  in  the  arms.  A 
physician  was  called,  who  gave  a  medicine  which  caused  vomiting, 
after  which  there  was  profuse  cold  perspiration.  Sjniiptoms  grad- 
ually passed  off,  and  by  3  P.  M.  of  the  following  day  he  was  well, 
with  the  exception  of  weakness  and  a  nimib  feeling  of  the  skin.  A 
drachm  of  fhe  fluid  extract  of  ergot  was  ordered  to  be  given  every 
hoiu-  until  four  doses  had  been  taken.  On  the  17th,  he  reported  him- 
self as  much  better.  Soon  after  taking  the  first  dose  of  ergot,  he 
found  his  strength  improved.  He  now  felt  well,  except  a  "  trembling  " 
in  the  chest.    Advised  not  to  resume  work  in  the  caisson. 

Case  XXIII. — Charles  Ward.  Began  work  May  17th,  and  con- 
tinued through  both  watches,  though  advised  to  omit  the  afternoon 
watch  for  the  first  day  or  two.  After  coming  up  the  second  time,  he 
felt  some  pain  in  the  legs.  Did  not  work  again  until  the  20th,  when, 
after  the  first  watch,  he  was  taken  with  numbness  in  the  left  leg, 
and  partial  loss  of  motion.  When  I  saw  him  on  the  21st,  the  sensi- 
bility in  the  affected  part  was  yeiy  much  blunted,  but  the  power  of 
motion  was  fully  restored.  Temperatm'e  to  the  hand  sensibly  lower 
than  in  the  other  leg.  Xo  pain.  Complaint  of  a  ''Avant  of  hold 
upon  the  ground  "  in  attempting  to  walk. 

Cold  water  was  poured  upon  the  lower  part  of  the  spine  for  several 
minutes,  after  which  there  was  a  decided  improvement  in  the  leg. 
He  was  able  to  walk  home ;  but  did  not  report  again,  and  I  lost  sight 
of  the  case. 


48 


Case  XXIV.— Fred.  Wilkinson.  Taken  May  21st,  after  the  second 
watch,  with  pain  in  the  right  knee.  Considerable  swelling  above 
and  internal  to  the  patella.  Slight  elevation  of  temperature.  Re- 
lieved by  the  cold  douche. 

The  minutes  of  the  following  case  were  kindly  furnished  me  by 
Dr.  Walter  Reed,  of  the  Brooklyn  City  Hospital,  and  are  so  interest- 
ing that  I  transcribe  them  in  full : 

Case  XXV. — "Michael  Madigan,  age  36,  Ireland,  laborer,  admitted 
March  26th,  1872.  A  large,  robust  man ;  states  that  he  has  been 
working  on  the  East  River  Bridge  for  three  months  past,  and  that 
for  several  weeks  x)ast  has  been  under  a  heavy  atmospheric  pressure 
(about  30  lbs.) 

"March  25th,  about  noon,  after  coming  up  from  the  caisson,  was 
taken  with  cramps  in  his  stomach,  which  required  a  dose  of  medi- 
cine for  their  relief.  He  then  went  to  his  dinner,  after  which  he  re- 
turned to  work,  but  felt  so  weak  in  the  legs  and  in  the  small  of  the 
back  that  he  was  compelled  to  leave  off.  Was  carried  home  and  put 
to  bed.  Did  not  have  much  pain  in  the  legs  or  back,  but  a  feeling  of 
extreme  weakness.  Slept  but  little  during  the  night,  and  in  the 
morning  found  that  his  legs  were  powerless,  nor  could  he  pass  his 
water,  which  had  to  be  duawn  with  a  catheter.  On  admission  there 
was  found  to  be  paralysis  of  the  legs,  with  slight  diminution  of 
sensibility.  No  pain  in  limbs.  Slight  tenderness  on  pressure  over 
the  lumbar  vertebrae.  Paralysis  of  bladder.  Urine  drawn  off ; 
quantity,  8  oz.  Acid  reaction  :  no  albumen.  Dry  cups  applied  to  the 
lower  part  of  the  spine.  Ordered  liq.  amnion.,  acetatis,  to  be  re- 
peated in  an  hour.    At  bed  time  potas.  bromid.  grs.  40. 

"March  27th.  Find  patient  improved.  Slept  well  during  the  night. 
Took  some  breakfast.  Can  move  his  right  leg  to  a  considerable  ex- 
tent ;  left  leg  powerless.  Has  slight  pain  in  the  back.  Urine  drawn 
off,  8  ozs. ;  acid.    P.  M. ,  to  re-apply  dry  cups  to  spine. 

"March  28th.  Can  move  both  legs  very  well.  Is  able  to  stand,  but 
his  knees  soon  bend  under  him.    Urine  drawn  off.    Cups  re-applied. 

' '  March  29tli.  Can  stand  up  and  walk  a  few  steps,  though  this  re- 
quires some  exertion.    Cups  again  to  the  spine.    Urine  drawn  off. 

"  March  31st.  Still  improves  ;  walked  to  the  water-closet  and  had  a 
movement  of  the  bowels.  This  is  the  second  movement  since  admis- 
sion.   The  first  was  an  involuntary  evacuation  in  the  bed. 

"  April  2d.  The  patient  has  regained  the  power  over  his  bladder, 
and  passes  his  urine  twice  a  day.    Feels  much  stronger. 

"April  5th.  Patient  has  been  walking  about  the  yard.  Says  he 
feels  well,  except  a  slight  weakness  in  his  back.    Discharged  cured." 

For  some  time  after  his  discharge  from  the  hospital,  this  patient  re- 
mained very  feeble,  and  the  catheter  was  occasionally  required  to  re- 


49 


lievc  the  bladder.  He  was  confident  that  he  received  great  benefit 
from  the  dry  cups  while  in  the  hospital,  feeling  better  each  time  as 
soon  as  they  were  applied.    In  this  statement  Dr.  Reed  concuiTed. 

Case  XXVI. — Reardon,  England,  38,  corpulent,  began  work  on 
the  morning  of  May  17th  ;  was  advised  to  work  only  one  watch  the 
first  day,  but,  nevertheless,  feeling  perfectly  well  after  the  first 
watch,  went  down  again  in  the  afternoon.  The  pressure  at  this  time 
was  about  35  lbs. ,  the  duration  of  the  morning  shift  2^  hours,  that 
of  the  afternoon  shift  2  hours.  Immediately  after  coming  up  from 
the  second  watch  Reardon  was  taken  with  very  severe  pain  in  the 
stomach,  followed  by  vomiting.  In  a  few  minutes  the  pain  seized 
upon  the  legs,  which  soon  lost  the  power  of  motion,  though  they  con- 
tinued to  be  the  seat  of  extreme  pain,  and  were  not  entirely  insensi- 
ble to  pinching  or  pricking.  The  vomiting  continued  all  night,  and 
toward  morning  he  Avas  removed  to  the  Centre  street  Hospital,  where 
he  gradually  sank,  and  on  the  18th  died. 

The  autopsy  showed  a  slight  engorgement  of  the  lungs.  All  the 
other  thoracic  and  abdominal  viscera,  as  well  as  the  brain,  were 
healthy.  The  spinal  cord  was  found  to  be  intensely  congested,  and 
opposite  the  two  lower  dorsal  vertebra?,  there  Avas  an  extensive  effu- 
sion of  blood  pressing  upon  the  cord. 

Case  XXVII. — Patrick  McKay,  Ireland,  50.  Had  been  four  months 
at  Avork  in  the  caisson,  and  had  not  complained  of  ill-health.  On  the 
30th  of  April  he  remained  in  the  caisson  half  an  hour  beyond  the 
usual  time,  at  the  second  watch,  the  pressure  being  about  34  lbs. 
Some  other  persons  who  were  Avitli  him  in  the  lock,  AA'hen  about  leav- 
ing, found  that  he  was  sitting  with  his  back  against  the  Avail  of  the 
lock,  quite  insensible.  He  was  at  once  carried  up  to  the  surface,  and 
removed  to  the  Park  Hospital,  Avhere  I  saw  him  shortly  afterwards. 
He  Avas  there  in  an  unconscious  condition  ;  face  pale  and  dusky  ;  lips 
blue  ;  pulse  irregular  and  feeble.  Under  the  administration  of  stimu- 
lants, he  recovered  some  degree  of  consciousness,  and  begged  inces- 
santly for  water.  The  urine  As^as  draAA^n  with  a  catheter,  and  found 
to  be  intensely  albuminous.  Paroxysms  of  convulsions  soon  set  in, 
in  one  of  Avhich  he  died,  nine  hours  after  the  attack. 

The  autopsy,  at  AA^hich  I  Avas  not  present,  showed  that  all  the 
organs  Av^ere  healthy,  except  the  kidneys,  Avhich  Avere  the  seat  of 
Bright's  disease,  and  were  very  much  altered  in  structure. 

In  this  case  the  effect  of  the  compressed  air  was  merely  to  hasten 
an  event  which,  at  best,  could  not  have  been  very  long  delayed. 

Case  XXVIII.— (Frangois).  Mirant.  Had  suffered  previously 
from  severe  pains  in  the  chest  and  limbs,  which  compelled  him  to 
give  up  work.  Sometime  afterward,  Avhen  the  pressure  was  4  at- 
mospheres, he  resumed  work  for  a  single  day — the  labor  being  exces- 


50 


sively  severe.  He  suffered  no  incouveuience  apparently,  however, 
and  after  leaving  the  caisson,  washed  his  face  and  hands  as  usual. 
A  moment  after  he  fell  senseless,  and  in  15  minutes  was  dead. 

The  autopsy  was  made  by  a  medical  commission  appointed  by  the 
authorities  of  Valenciennes.  The  menniges  were  found  to  be  inject- 
ed, and  the  sinuses  distended  with  dark  blood.  The  brain  itself  was 
also  congested.  The  spinal  canal  was  not  opened.  The  lungs  were 
somewhat  congested,  especially  at  the  base,  where  they  were  less 
crepitant  than  natural,  though  still  floating  in  water  even  when  cut 
into  small  pieces.  There  was  general  congestion  of  the  abdominal 
viscera.    (Annales  d'Hyg.  de  Pub.  et  Med.    Legale,  1860.) 

Case  XXIX. — The  following  description  of  the  post-mortem  ap- 
pearances in  a  case  occurring  at  St.  Lou^s,  is  from  Dr.  Jaminet's  re- 
port, and  may  be  taken  as  a  type  of  the  morbid  anatomy  of  the  Cais- 
son Disease. 

"Henry  Krausman,  27  years  ;  nativity,  Germany  ;  admitted  into 
the  hospital  March  22d ;  died  the  23d.  The  whole  contents  of  the 
cranium  were  found  highly  congested,  with  effusion  beneath  the 
arachnoid,  the  vessels  of  the  latter  membrane  being  highly  injected. 
Blood  oozed  freely  from  the  substance  of  the  brain  on  section.  The 
spinal  cords  presented  pathological  conditions  precisely  like  those  of 
the  brain,  with  the  addition  of  the  existence  of  clots  of  extravasated 
blood  at  different  points  inside  the  dura  mater.  There  was  alse  a 
congested  condition  of  the  thoracic  contents,  less  marked  probably  in 
the  lungs  than  in  the  other  organs.  The  abdominal  viscera  were 
very  highly  congested,  with  extravasation  of  blood  in  the  kidneys 
The  mucous  membrane  of  the  bladder  was  healthy,  and  a  small 
quantity  of  bloody  urine  was  in  the  bladder. " 

Case  XXX. — John  Myers,  aged  about  40  years,  a  native  of  Ger- 
many, of  a  stout,  heavy  build,  commenced  work  in  the  caisson  for 
the  first  time  on  the  22d  of  April,  1872,  the  pressure  then  being 
about  34  lbs.  to  the  inch. 

He  worked  during  the  morning  shift  of  2^  hom's  without  in- 
convenience, and  remained  about  the  yard  for  nearly  an  hour  after 
coming  up.  He  then  complained  of  not  feeling  well,  and  started  for 
his  boarding-place,  which  was  but  a  few  rods  distant.  As  he  passed 
through  the  lower  stor}^  of  the  house,  on  his  Avay  to  his  own  room, 
which  was  on  the  second  floor,  he  complained  of  pain  in  the  abdo- 
men. While  ascending  the  stairs,  and  when  nearly  at  the  top,  he 
sank  down  insensible,  and  was  dead  before  he  could  be  laid  upon  his 
bed. 

The  autopsy,  which  took  place  at  the  morgue,  was  made  by  Dr. 
Janeway.  It  showed  that  the  brain,  heart,  kidneys,  and  larynx  were 
perfectly  normal.  The  only  lesion  discovered  was  in  the  lungs,  which 


51 


were  congested  to  a  very  remarkable  degree.  The  entire  extent  of 
both  lungs  presented  an  appearance  closely  resembling  that  of  a 
highly  congested  spleen.  The  spinal  canal  was  not  opened ;  but 
nothing  was  found  elsewhere  to  account  for  the  sudden  engorgement 
of  the  lungs. 


CHAPTER  SEVENTH. 

SUGGESTIONS. 

As  it  is  now  demonstrated  that  the  method  by  compressed  au"  is  ap- 
plicable to  a  gi'eat  range  of  engineering  operations,  and  offers  many 
peculiar  advantages,  it  is  extremely  desu'able  that  the  principal  ob- 
jection to  its  emplopiient,  viz.,  the  discomfort  and  danger  to  the 
workmen,  should  be  reduced  to  a  minimum.  To  this  end  I  would  of- 
fer the  following  suggestions,  drawn  from  my  own  experience  and 
that  of  European  and  American  observers,  to  whose  writings  I  have 
had  access. 

It  is  exceedingly  desu'able  that  the  men  should  be  under  control  to 
a  certain  extent  during  the  intervals  of  work.  Excessive  use  of  in- 
toxicating liquors  should  be  prevented ;  regular  hours  for  sleep  and 
for  meals  insisted  upon,  and  sufficient  nutritious,  digestible,  and 
properly  cooked  food  should  be  provided.  The  men  should  sleep  in 
comfortable  beds  and  in  properly  ventilated  apartments. 

All  this  is  manif  estl}'  unattainable  if  the  men  live  in  homes  of  their 
own  choosiug.  If,  therefore,  any  great  work  by  the  aid  of  com- 
pressed au-  is  to  be  undertaken,  the  preparations  for  it  should  include 
whatever  is  necessary  for  housing  and  feeding  the  men  at  a  conven- 
ient place  near  to  the  work.  For  this  purix)se  temporary  barracks 
may  be  erected  in  an  enclosure,  which  the  men  should  not  be  permit- 
ted to  leave  except  under  proper  restrictions. 

The  food  should  be  furnished  by  the  employers,  be  of  good  quality, 
embrace  a  sufficient  variety,  and  be  prepared  by  competent  cooks. 
Sleeping  apartments  should  be  provided,  allowmg  at  least  800  cubic 
feet  of  air-space  to  each  man.  and  with  facilities  for  efficient  ventila- 
tion. 

A  hospital  should  be  arranged  v.'ith  a  sufficient  number  of  beds, 
and  fitted  ^y\th  every  appliance  necessary  for  treating  patients  during 
their  entire  illness.  The  hospital  to  be  in  charge  of  a  competent 
steward,  under  the  supervision  of  a  physician,  who  should  attend  a 
portion  of  each  day. 

Of  com-se  this  implies  that  only  single  men  shall  be  employed,  and 
that  they  shall  agree  at  the  outset  to  submit  to  a  quasi  military 
rule. 


52 


Where  the  number  of  men  is  considerable,  as  would  l3e  the  case  in 
any  large  work,  the  company  could  carry  out  the  above  suggestions 
economically  to  themselves,  and  after  deducting  the  cost  from  the 
pay  of  the  workmen,  there  would  remain  to  the  latter  more  than 
they  would  have  left  after  paying  their  board  in  the  usual  way.  At 
the  same  time  the  men  would  be  so  much  more  comfortable  than  if 
left  to  provide  for  themselves,  that  they  would  value  the  position, 
and  the  fear  of  being  discharged  would  be  a  sufficient  restraint  upon 
them.  The  tendency,  too,  w^ould  be  toward  securing  at  the  begin- 
ning of  the  work  a  set  of  men  who  would  continue  to  the  end.  These 
men  commencing  when  the  pressure  was  slight,  would  not  be  affected 
by  its  gradual  increase,  thus  avoiding  the  great  danger  which  attends 
those  who  begin  work  for  the  first  time  after  the  pressure  has  at- 
tained a  high  figure.  I  am  satisfied  that  it  is  by  attention  to  this 
point  more  than  by  anything  else,  that  the  suffering  and  danger  re- 
sulting from  the  use  of  compressed  air  may  be  diminished.  (See 
page  36.) 

New  hands  should  not  be  allowed  to  work  in  the  caisson  more 
than  one  w^atch  in  each  day  for  the  first  week,  after  which  half  the 
usual  second  watch  might  be  added  for  another  week,  at  the  close  of 
which  the  full  time  could  be  entered  upon. 

Since  much  of  the  work  on  the  pier  above,  as  well  as  in  the  caisson 
below,  is  unskilled  labor,  it  could  readily  be  so  arranged  that  tliC 
gangs  could  work  on  alternate  days  in  the  compressed  and  in  the 
external  air.  The  advantage  of  an  interval  in  the  caisson  work  is 
immediately  apparent,  the  cases  of  sickness  being  notably  diminished 
by  even  a  single  day's  intermission. 

The  rules  given  at  p.  15  are  important,  and  their  observance 
should  be  strenuously  insisted  upon. 

The  men  should  be  selected  as  far  as  possible  from  those  who  are 
of  a  spare  and  wiry  build,  and  no  one  should  be  accepted  who  has  a 
tendency  to  corpulency. 

The  lock-tenders  should  be  selected  with  special  reference  to  their 
trustwortliiness,  and,  if  it  is  found  that  they  cannot  be  depended 
upon,  the  au--cocks  should  be  so  arranged  that  the  aperture  can  be 
graduated  from  time  by  the  engineer  in  charge,  so  as  to  prevent  the 
possibility  of  a  too  rapid  change  of  pressure. 

In  entering  the  caisson,  at  least  three  minutes  should  be  allowed  in 
the  lock  for  each  additional  atmosphere  of  pressure,  and  at  least  five 
minutes  in  coming  out. 

As  for  the  number  of  hours  of  work  daily,  the  rule  given  by  Mr. 
Collingwood  will  serve  as  a  general  guide.  "  Taking  it  for  granted 
that  12  hours  is  the  extreme  time  that  a  man  can  labor  without  detri- 
ment to  health,  in  an  ordinary  atmosphere,  then  with  a  pressure  of 


53 


two  atmospheres,  or  15  lbs.  additional  pressure,  lie  can  labor  about 
one-half  that  time  ;  with  three  atmospheres,  about  one-third  of  that 
time ;  and  with  four  atmospheres  about  one-fourth  of  that  time.  In 
other  words,  the  time  is  inversely  as  the  pressure."* 

Whenever,  for  any  cause,  a  sudden  increase  of  pressure  is  demand- 
ed, the  watch  should  be  shortened  to  a  corresponding  extent. 

The  air-locks  should  be  placed  at  the  top  rather  than  at  the  bottom 
of  the  shaft,  in  order  that  the  stair  may  be  climbed  in  the  compressed 
air,  instead  of  immediately  after  leaving  the  lock,  when  the  system 
is  more  or  less  prostrated  by  the  change  taking  place  in  the  circula- 
tion. If,  for  any  reason,  it  is  impracticable  to  have  the  air-lock  at 
the  top  of  the  shaft,  an  elevator  should  be  emploj^ed  to  lift  the  men 
to  the  surface. 

Care  should  be  taken  to  maintain  the  air  in  the  caisson  at  a  suffl-  . 
cient  degree  of  purity,  as  there  may  be  a  Avide  difference  between 
the  amount  of  air  required  to  supply  the  necessary  mechanical  condi- 
tions for  carrying  on  the  work,  and  the  quantity  demanded  for  the 
health  of  the  workmen.  A  rough  but  useful  test  for  the  presence  of 
carbonic  acid  in  the  air  has  already  been  described  at  p.  14.  This  is 
very  easily  applied,  and  should  be  frequently  resorted  to  when  there 
is  the  least  doubt  as  to  the  sufficiency  of  the  air  supply.  A  compari- 
son of  the  results  with  those  obtained  in  some  fairly  ventilated 
apartment,  will  give  an  idea  of  the  amount  of  impurit}^  in  the  air  of 
the  caisson.  The  comparison  will  be  aided  by  allowing  the  carbonate 
of  lime  formed  to  settle  to  the  bottom  of  the  test  tube,  where  the 
quantity  caif  be  more  readily  appreciated. 

ANDEEW  H.  SMITH. 


*  Traus.  Am.  Society  of  Civil  Engineers,  p.  133. 


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